low-key advertisement, because this game is pretty fun so far:
I used to play on a private server so I could level up alts fast in order to do the endgame group content. I gave up because even with fast xp you still have to do all of the annoying shit like farming flasks, reputation grinds, etcetc.
Fellowship (on steam) just released into EA and it is basically WoW's M+ dungeon system without the MMO. It uses a hero system instead of class + talent spec. So, for example, Helena is a hero that plays like a hybrid Prot Warrior/Prot Paladin, Sylvie is a Reso Druid, Tariq is an Arms warrior.
There's still gear progression and build customization (tinkets, weapon abilities, talents) but you don't have to do 30 hours of questing to make an alt.
Works just fine on Linux (check protondb, there's a required command line option).