For splitting the app in the taskbar I found it useful to “install” the PWA (you got to find the hidden option in chrome for that…), if it’s supported by the website… It still uses the same cookies and addons, but at least it doesn’t easily get merged with the main browser window and behaves like a proper desktop application. I mainly use firefox though and it doesn’t support PWAs (easily, at least). It’s a shame it’s not more common, because it’s a much better way to run software than the many electron apps, each having their own chromium installation (no download, no long installation process, full sandboxing, and you can have addons & adblockers affect the pwa!)
For fstab editing, try running “mount <path>” and check if it succeeds before rebooting, so you can still edit if there are mistakes. FYI if you do a sytax mistake in fstab the entire OS might fail to boot. If it happens don’t panic, it’s easy to fix: you can use the install usb drive to edit fstab on your disk and try again (no need to reinstall!)
There are also graphical tools. I never used them, but it might be easier if you are not feeling super sure on what to do: https://superuser.com/questions/346606/is-there-any-gui-tool-to-configure-etc-fstab
I also use steam to manage external launchers. It’s a bit clunky, but it keeps proton updated and works quite well once it’s set up.
Welcome to linux, and do ask around for help / tips if you need!