What you are asking for seems not permissible according to the fatwas I've consulted.
However eating with non-Muslims is permissible as is stated in this fatwa:
The scholars of the Standing Committee were asked:
What is the ruling on eating, drinking, sitting with and interacting with a disbeliever? Does it put one beyond the pale of Islam?
Merely eating with a disbeliever, sitting with him and interacting with him when selling to him or buying from him, or other interactions in which there are worldly benefits that do not have any harmful repercussions for the Muslims in their religious or worldly affairs, does not put one beyond the pale of Islam. Rather treating the disbelievers with kindness and being nice to them is not regarded as sinful so long as they are not fighting us on account of religion or waging war against us. Allah, may He be exalted, says (interpretation of the meaning):
“Allah does not forbid you to deal justly and kindly with those who fought not against you on account of religion and did not drive you out of your homes. Verily, Allah loves those who deal with equity.
It is only as regards those who fought against you on account of religion, and have driven you out of your homes, and helped to drive you out, that Allah forbids you to befriend them. And whosoever will befriend them, then such are the Zalimoon (wrong-doers those who disobey Allah)”
(al-Mumtahanah 60:8-9). (Source: fatwa islamqa #177012)
Let's make some brainstorming on your case:
- Going to a restaurant: Based on your post I guess you mean going to a non-Muslim restaurant. In such restaurant it is expected that they do sell and serve alcohol beside other meals that include alcohol or pork etc.. This already puts a huge doubt on whether or not it is permissible to go there, even if your friend ate halal food.
"The Messenger of Allah (ﷺ) cursed ten involved in wine: The one who presses it, the one who has it pressed, its drinker, its carrier, and the one it is carried to, its server, its seller, the consumption of its price, the one who purchases it and the one it was purchased for."
I heard Allah's Messenger (ﷺ), in the year of the Conquest of Mecca, saying, "Allah and His Apostle made illegal the trade of alcohol, dead animals, pigs and idols." The people asked, "O Allah's Messenger (ﷺ)! What about the fat of dead animals, for it was used for greasing the boats and the hides; and people use it for lights?" He said, "No, it is illegal." Allah's Messenger (ﷺ) further said, "May Allah curse the Jews, for Allah made the fat (of animals) illegal for them, yet they melted the fat and sold it and ate its price."
- Your non-Muslim friend: Assuming the doubt above can be lifted, by inviting this non-Muslim what do you intend? Or what is the outcome of this invitation? Are you hoping to invite him to Islam? Is this person in need of support? any other reason is usually regarded as not weighty enough to make such an invitation lawful and permissible.
Sadaqah may not be given to rich man, with the exception of five classes: One who fights in Allah's path, or who collects it, or a debtor, or a man who buys it with his money, or a man who has a poor neighbour who has been given sadaqah and gives a present to the rich man.
(Sunan abi Dawod)
"Giving charity to a poor person is charity, and (giving) to a relative is two things, charity and upholding the ties of kinship."
The ahadith above show to whom charity might be given, under charity we may also count gifts and invitations.
The fatwas I've consulted literally follow the advice:
The Prophet (ﷺ) said: Associate only with a believer, and let only a God-fearing man eat your meals.
(Sunan abi Dawod)
Therefore the fatwa I've linked above further says:
With regard to sitting with them, eating with them and interacting with them on the basis of friendship, brotherhood, love and spiritual harmony, this is not permissible; rather it may amount to kufr (disbelief) that takes one beyond the pale of Islam in the case of one who approves of them and their religion, loves them, is sincere towards them or supports them against the Muslims, and the like – Allah forbid. Allah, may He be exalted, says (interpretation of the meaning):
“O you who believe! Take not for Auliya (supporters and helpers) your fathers and your brothers if they prefer disbelief to Belief. And whoever of you does so, then he is one of the Zalimoon (wrong-doers, etc.).
Say: If your fathers, your sons, your brothers, your wives, your kindred, the wealth that you have gained, the commerce in which you fear a decline, and the dwellings in which you delight are dearer to you than Allah and His Messenger, and striving hard and fighting in His Cause, then wait until Allah brings about His Decision (torment). And Allah guides not the people who are Al-Fasiqoon (the rebellious, disobedient to Allah).”
“You (O Muhammad SAW) will not find any people who believe in Allah and the Last Day, making friendship with those who oppose Allah and His Messenger (Muhammad SAW), even though they were their fathers, or their sons, or their brothers, or their kindred (people). For such He has written Faith in their hearts, and strengthened them with Rooh (proofs, light and true guidance) from Himself. And We will admit them to Gardens (Paradise) under which rivers flow, to dwell therein (forever). Allah is pleased with them, and they with Him. They are the Party of Allah. Verily, it is the Party of Allah that will be the successful”
“O you who believe! Take not the Jews and the Christians as Auliya (friends, protectors, helpers, etc.), they are but Auliya to one another. And if any amongst you takes them as Auliya, then surely he is one of them. Verily, Allah guides not those people who are the Zalimoon (polytheists and wrongdoers and unjust)”
Shaykh ‘Abd al-‘Azeez ibn Baaz, Shaykh ‘Abd ar-Razzaaq ‘Afeefi, Shaykh ‘Abdullah ibn Ghadyaan, Shaykh ‘Abdullah ibn Qa‘ood
End quote from Fataawa al-Lajnah ad-Daa’imah, vol 3, 1/431-433
In Islam even in the case if one buys non-halal food (alcohol or pork) by mistake it is neither allowed to sell it to a non-Muslim nor to give it as a gift to him. See for example fatwa islamqa #245688.