I’ve played the first five Civ games and I have fond memories of buying units with diplomats! There’s also FreeCiv which is an open source project that’s very similar to Civ2 but probably supports modern hardware better. It’s been built for android but from what I understand they’re built by third parties so if you’re tech savvy or feeling adventurous you could build it yourself. I played it many years ago in a really rough state where nothing was explained and my own knowledge of Civ 2 was the only thing that made it playable but from what I have heard it’s much better now.

Fun fact, Civ1 was ported to the SNES and Civ2 was ported to the PlayStation.