In general, guitarists are handled about the same as the other folks: You’re expected to at the least, know several chords and be able to play rhythm and change chords pretty smoothly.
Beyond that, it’s a plus if you can offer some songs that you sing, at slow tempos, with easy chords, preferably in G. If you can do any soloing, that’s fine, but it’s not expected. We are mainly about:n1. Getting people comfortable in a jamming situation, following along.n2. Teaching people how to be valuable contributors to a jam session (singing lead, singing harmony, taking solos, leading the group for a song at a time). Some people are ready for this, some not. All are welcome.
My wife Joan is a good rhythm guitar player, and both she and I will give pointers to the various guitarists regarding a good balance of sound, bass runs, etc. Not a lot of specific instrument instruction, but pointers as a person’s playing relates to helping the group sound better.
In sum, you will get a good workout on your guitar, and learn some of the fine points of how to handle your guitar at a jam, building confidence as you go.n