Background: I sang in chorus (with occasional solos) from children's choirs most of the way through college. There's something wonder-ful in creating tones and songs with other people. Most of my group singing since then has been via occasional hymn-singing when I'm visiting my dad, and folk music at dance camps. The local choirs around don't especially pull at me -- mainly because I think the commitment to weekly rehearsal and performance dates would weigh on me. Singing choral pop music doesn't pull at me at all (too often too schmaltzy, though I enjoy listening to the occasional rockapella). Church choirs mean a twice a week commitment, and would probably lead to some degree of pressure to join the church. I tried shape note singing once (I know that's not a fair trial) but it was a long drive (to go often) and a high entry barrier (different notation, cognitive dissonance). But I like listening to much choral music.
I was intrigued to come across a very local group -- 5 minutes by car from my house, or a half-hour walk in good weather -- which does something which I hadn't realized was a thing, called Circlesinging. If you think of some of Bobby McFerrin's group numbers, that might give you the idea -- and some of the leaders of the local group have trained with him. I tried it out on Sunday (they meet second Sunday afternoons), and ended up really liking it. It's kind of a choral improv group, where we are led to sing syllables in rounds, and the leaders (and volunteers, when they can get them) sing on top of that. The lead stays with a section (e.g., altos) until they get their bit (a syllable, a measure, a couple of measures at most), and then goes on to the next section (e.g., second sopranos) and builds on that. There were jazz and blues elements, percussive mouth/body sounds, and sometimes we snapped fingers or stood up and kind of stamped/marched as we sang. Sometimes actual words were used. :-) Occasionally it was more call-and-response. There was a game where one person in the circle started with a sound/rhythm, and then the next person added something to harmonize/complement what they were doing, and we went all the way around the circle. Of course that kind of freestyle could be far more intimidating to some people than just a different notation system, but it all felt playful and warm to me.
Some vids: