Start with one regular room
Pick something that runs every week. Commit to three sessions. Don't evaluate until then. The first time is strange for everyone. The third time is familiar.
Be the man who says hello
In any group, a small number of men do the work of welcoming. Be one of them. It costs nothing and it shortens the loneliness arc for the next man through the door.
Carry it sideways
Real community shows up between sessions — a text, a check-in, a coffee. Once you've found two or three men you trust, take it out of the room sometimes. That's how it becomes a life, not a meeting.