I recently started learning and playing poker, and I mostly play with fake money. Here’s what I’ve used so far:

Pokerstars and GGPoker both have fake money options that you can play without depositing money. I used Pokerstars for a while as it was the only client I could get working on Linux (using bottles). They both have good mobile apps. I prefer GGPoker’s interface so I’ve been using my Windows dual boot to play that when I want to on my computer.

Poker Brawl is a phone app where you can play correspondence heads-up poker with an ELO rating system. It’s correspondence , so you only have to make a move once every three days. It’s heads-up only, though.

I’ve found playing on real poker platforms with fake money to be best in terms of somewhat emulating real poker in terms of player behavior.

Feel free to comment with any questions and I’ll try to help