If you told me I had to go 100% FOSS tomorrow, I could do it pretty easily, except for those two apps.
95% of my games are through Steam, and 95% of all my friends, family, and online community are in Discord. I could probably even dump Discord and convince some of my closest friends and FAM to switch to a Matrix client or something. But giving up Steam would mean I would basically be giving up nearly all gaming in my life.
And contrary to many other FOSS enthusiasts, I actually think Steam and Discord are great apps. I've rarely had issues with them, especially Steam. The UI is decent, the features are great, (Steam game join, Workshop mods, etc.) And Discord works really well on Linux for me, and GrapheneOS on my phone.
Of those two, I'd rather dump Discord. Valve is generally a very FOSS friendly company and pretty consumer friendly compared to most multi-billion dollar corpos. And what they've done recently for Linux gaming over the last few years with Proton, the Steam Deck, etc has has made gaming on Linux a wonderful experience for me.
Recently I have been trying to get into more FOSS games and GoG DRM-free games as an insurance policy for what I know is coming down the line one day. Gabe will either retire, pass away, or be bought out by a corpo/capital investment firm and Valve will become victim to the enshitification effect like all other proprietary software.
There is a small hope I have, idk if this is even possible, but what if Gabe chooses to open source some or all of the Steam code instead of letting it get bought out or taken over by somebody else? That would allow for the FOSS community to fork it and build a FOSS Steam.
Like I said though, a pipe dream for now. Long live FOSS!
I could probably dump discord, but there's just no alternative to Steam. It succeeded, where literally every other publisher failed, to unify game distribution on the PC. Even if valve made steam itself FOSS and let anyone clone it, there's no chance in hell they'll get anyone but the most indi of studios to launch anything on it, let alone exclusively.
Of all the proprietary codebases and their companies, Steam and Valve are the only ones I respect.