Shoutouts

Thanks to the following commenters below for additional recommendations that I added to this post!

• bruhduh
• Toes

Free Open Source Alternatives

[Visual/Graphical]

For all visual/graphical artists I would personally recommend switching from Photoshop over to

• KDE's Krita
  • Licensed under: GPLv-3.0 or later
  • Flathub

• GIMP
  • Licensed under: GPLv-3.0 or later
  • Flathub

[Audio]

For audio migration I'd recommend switching from Soundbooth to

• Tenacity
  • Licensed under: GPLv-2.0 or later
  • Flathub

• LMMS
  • Licensed under: GPLv-2.0 or later
  • Flathub
    • Status: "Unverified"

[PDF]

Acrobat Reader to

• MuPDF
  • Licensed under: AGPLv-3.0 or later
  • F-Droid

• KDE's Okular
  • Licensed under: GPLv-2.0 or later
  • Flathub

[Video]

Premiere to

• Shotcut
  • Licensed under: GPLv-3.0 or later
  • Flathub

• Kdenlive
  • Licensed under: GPLv-3.0 or later
  • Flathub

• OpenShot
  • Licensed under: GPLv-3.0 only
  • Flathub
    • Status: "Unverified"

There's also an excellent thread started by urska@lemmy.ca