Discord, definitely!! It might be hard to ditch but it's worth trying. I was never a big fan of it so it was kinda easy yet I still miss being able to contact some people on there. But the more people continue using it, the harder it will be to change things.
Spotify and Chromium, I agree on both as well. Try the options mentioned above concerning Spotify. And yeah, Music streaming is a hard one... I have a dedicated mobile device for Music streaming platforms of this kind if I feel the itch as well as a modded ipod for on the go. Highly recommend getting into a habit of buying Music (digital/physical) and listening stuff you actually own on desktop. Simple cmus or sth will do the job.
Maybe Librewolf or other Firefox fork for Browser.
Edit: typo. Edit 2: I'd keep a chromium-based Browser of some sort, you might need it sometime for something. Just use different Browsers for different things.
Great tip, thanks, I tend to overlook that option. My local library does offer audiobooks indeed but as I don't reside in a english-speaking country I highly doubt it would be available.