I run a cluster on 3 nucs. You could also do it on one nuc, or any other machine. Nucs aren't discontinued, they're just owned by Asus now.
Fair warning that going from zero to fully-automated-setup ansible+k3s+flux+rook+nginx+cloudflared is both very confusing and not very educational
I started with that template and ran into issues that were like 5 layers deep in infrastructure that I'd never touched that was auto-deployed and ended up just starting over from scratch. The final product from the onedr0p template is super slick but there's a lot there and you don't get any chance to understand it one piece at a time really.
I totally understand, I just found that there was more to learn by actually "getting your hands dirty" and standing that up more from scratch instead of deploying it all via the nice scripts and recipes from community repos.