The most popular that I use are:

• • -Firefox
• • -Librewolf
• • -Jellyfin (i was astonished that this piece of software wasn't mentioned before)
• • -SMPlayer (imho the best front end for MPV)
• • -shutdown command (i use it daily)
• • -Lutris
• • -Wine
• • -Piper (to manage keybings on the mouse with a gui) (is also the only one that I found that works with my G502, if you have an alternative please tell me, i want to check it out)
• • -ckb-next (for managing leds and keybindings for my keyboard)
• • -openRGB

Honorable mention: Molly (the FOSS version, a privacy focused client for Signal)

Edit: Almost forgot about QEMU+kvm for virtualization