They don't even have to be explicitly NB friendly, just not a dick and able to work with people with different desires and goals.

The last gym staff I had dealings with: one didn't understand I wasn't interested in becoming some Action Man looking Manly-Man-man and just wanted to keep fit.
Another told me gyms are mostly a waste as he would go and do pull-ups from a tree in a park and use it's equipment and had a home gym (the nearest park was 40mins away from me and I had a small studio).
A third told me unless I was coming in at least 4 times a week I was wasting time as I had to hit my goal in 3 months or less and then up it further as maintenance is dumb.

Suffice to say, my bar is low.
All I want is just a human to teach me and help me.

I'll even take recommendations for LGBTQ+ walking groups (not running, not now, not there yet) in London (I found a few but lacking FB etc it's hard to follow), and my biggest fear is "breaking in to" these groups, I've found they can be close