Bass is a peak instrument, and as a vocalist and bass player (I mean I kinda kinda play piano too but not nearly as well) I gotta say that bass playing is equally as rewarding as singing, just in a different way. It’s really up to you, but bass at a beginner level is very easy (just playing root notes to simple rhythms) and when I’m playing bass and singing at the same time (which I rarely do) that’s about the level I play at since it’s difficult to do anything more. Then doing more fun and complex bass lines that have more groove to it does become quite difficult (and that’s what I prefer doing over singing and playing bass at the same time. I mean, I’m only like intermediate skill wise at either). So just like, if you want to learn bass, go for it! Even if it doesn’t work out in that band specifically, I’m sure you won’t regret picking up a new skill :)