Linux

Congrats on your jump! May your move be a positive one!
I'm on the Arch side of things and don't touch Gnome a whole lot, so I probably won't be a lot of help, but one thing I might suggest is to be prepared for the sheer modularity of it all. It's no longer a Windows issue, likewise, it's not generally a Pop_OS issue, it's a specific app's issue. If your desktop misbehaves, it's likely Gnome (or Gnome extensions), if games aren't loading in general, it's probably Proton/Wine. I say this because it helps immensely to narrow down where an issue or incompatibility lies.

The modularity also has some really cool benefits to it though! If you find that you don't like your file explorer, install a different one. If you find that you prefer Plasma's customization but not ready to make a leap off of Gnome, install it alongside Gnome so you can try it out and see what you like or don't like about it.

The other thing I'd suggest is to be ready to rewire your brain on what apps you default to, just like you're doing with Lemmy & Reddit, but on a mass scale. It can be subtle differences like gNotes vs. Notepad, or as extreme as Krita vs. Photoshop. Getting familiar with the FOSS replacements for many of the common apps that you use will take you much further than trying to get familiar Windows apps to work on Linux.

Gaming: There's a lot to learn, but if you take it bites at a time, it'll make sense. Start with games on Steam, play some Windows games on Linux, note how freaking cool that is. Start to make use of ProtonDB.com to make some games work that might not out of the box, or optimize games you currently have working based on people's suggestions.
Small jump, ProtonUp, here you can install various runners, compatibility tools, and get your hands messy with the runner side of things. While I don't need ProtonUp very often, understanding runners can be invaluable, since you might benefit from using a GE version, or take for instance, when Overwatch 2 came out, it wouldn't run on Wine, but you could copy the runner from Bottles into Lutris and play off of that.
Then the big leap: Lutris and Bottles. These two are fairly similar, Lutris is predominantly for games that aren't in Steam, and Bottles is generally for applications. I use Bottles very little, because using Linux stuff on Linux will always treat you better than trying to get a Windows thing to work on Linux. Lutris has scripts to help install games for you, but its interface allows for more exploring what those properties on ProtonDB actually are and what they do for you. At this point, you can customize some of the compatibility tools to fit your liking or contribute back to others so they can also play things that may not already have a premade script.

Last and certainly not least: 3 expectations \

1. Be ready to be a self starter: if things go wrong, be ready to read some (fabulously written) documentation, pulling up some (well organized) logs, and doing some good old fashioned research. \
2. Do not be afraid to reach out for help: The Linux community is a passionate one that wants to see others thrive in it. If you have issues with Lutris, why not hop on their discord and get help directly from them for free? Most paid services (Windows) don't even offer that kind of support! \
3. People are people. I know this sounds obvious, but while Linux is fantastic and its community is wonderful, try not to take it personally if someone's difficult. Most people that support the Linux ecosphere are volunteers, they're not paid, some of them are really not good with people, and there's always a lot to do. Be patient with folks, temper expectations, and be ready to get your hands dirty with your computer, because while someone might be able to help guide you, it's going to be you pushing the buttons.
   
   Congrats again, my friend, and welcome to a big new world <3