With cats one is more work than two or three, except for litter box. Start with a fish is good advice.
Had GF that had a cat that died, got another. That one ran away and we couldn't find it. So, she went to the shelter and got another, that she decided to keep indoors, unlike the other. Then the other returned and there was a period of much jealousy. I think they finally got along OK.
My dad had a 20 gallon tropical fish tank in our family room which was a great source of pride for him. Of course, he tended it. I haven't had a single pet since leaving home. My dear dog died age two, had a habit of chasing cars. My parakeet was an equally sad story. My turtles always died young and look rather nasty IIRC when dead (maybe 2?). Our cats were ours, not mine. The subsequent dogs I didn't consider mine. I try to befriend cats that visit my yard but they have been generally skittish. I can't get within 10 feet of the one that's visited my yard pretty consistently for probably 7-10 years now.
I don't know. A fish sits there waving its fins. Moves, eats, gulps water. The idea does not thrill me. If I had a GF who wanted pets, I'd be all in. That's been my attitude. GF first!