As a gay male I never quite understood where Muslims were getting the prohibition for homosexuality. The people of Lut committed a specific act, intercourse from the rear area, this is the single act which is punishable in Islam, not for example two men pleasuring each other's genitals without the use of the anus. And even if homosexuality in general was prohibited, how do Muslims translate and equate this to a romantic relation between members of the same gender that avoids lustful actions, and what counts as lustful action, from what I know I as a male lower my gaze from females, and the awrah of a man in front of another man is debatable I think.
The Quran does not explicitly mention anal intercourse at all, rather what it condemns is more general:
ولوطا إذ قال لقومه أتأتون الفاحشة ما سبقكم بها من أحد من العالمين إنكم لتأتون الرجال شهوة من دون النساء بل أنتم قوم مسرفون
And [We had sent] Lot when he said to his people, "Do you commit such immorality as no one has preceded you with from among the worlds? Indeed, you approach men with desire, instead of women. Rather, you are a transgressing people."
This includes all acts between men that are motivated by desire.
Also the Quran commands men to protect their eyes (from looking with desire) and their private parts:
قل للمؤمنين يغضوا من أبصارهم ويحفظوا فروجهم
Tell the believing men to reduce [some] of their vision and guard their private parts.
Guarding them means from everyone unless explicitly permitted, and this permission exists only for their wives and female slaves:
والذين هم لفروجهم حافظون إلا على أزواجهم أو ما ملكت أيمانهم فإنهم غير ملومين فمن ابتغى وراء ذلك فأولئك هم العادون
And they who guard their private parts. Except from their wives or those their right hands possess, for indeed, they will not be blamed - But whoever seeks beyond that, then those are the transgressors.
Other men would come under "beyond that" and would be transgression and hence haram.
this is the single act which is punishable in Islam
Other sexual acts are also legally punishable. What you may be referring to is that this act is punishable with the Hadd, whereas lesser offences that do not fulfill the criterion of the Hadd are punishable with a Ta'zir.
the awrah of a man in front of another man is debatable
What is debated is marking the limits of the 'awrah between men. However 'awrah does exist and even the least opinion includes the genitals themselves.
لا ينظر الرجل إلى عورة الرجل
No man should look at the nakedness of another man.
Also this demarcation (for example navel to knees) is relevant for when there is no desire or fear of temptation (as is more commonly the case between members of the same gender). When desire and temptation arise then no part of the body should be seen.