You can play them on an emulator. You can even connect a Dualshock 3 controller to your PC, and it'll be just like playing on the "specialty hardware" it was made for.
Vivaldi also has a "window panel" that is basically a tree-style list in your sidebar of all your tabs across all windows and workspaces, and recently closed tabs and sessions.
Vivaldi's toolbar can be customized just like Firefox, but you additionally also get a bottom bar and a sidebar to place toolbar buttons on.
Vivaldi has a Spotlight-like search bar you can open with F2 to quickly find a page in your history or type any browser command like hiding the UI. You can also string multiple commands together and add them as a toolbar button.
You can add websites to your sidebar too to open them in a slide-out window of sorts (basically the same thing as Opera GX's sidebar).
You can tile multiple tabs to open them in a split or grid view, which I haven't found a way to replicate on Firefox so far.
And as someone else already mentioned, I personally find installing CSS and JS mods to be a lot more accessible on Vivaldi.
I also want people-owned website to take off, but as of right now there is little incentive for people to host their videos on their own when YouTube does it for free and gets you a huge audience.
For now, I have to choose between participating in the adblocker cat-and-mouse game, or just getting my Turkish "friend" to purchase YT Premium and being done with it.
Many games on Steam use Steamworks DRM despite being available DRM-free on other stores, one prominent example being Batman Arkham City.