Krita if you have an android device with a big screen.
Or Pocket Paint for a phone, but it's not a 'full' alternative IMO.
Different apps/F-Droid links:
File manager - Material Files.
Password Manager - KeePassDX (F-Droid).
Browser- Mull/Fennec F-Droid (F-Droid).
Gallery - Simple Gallery Pro (F-Droid).
Mail - FairEmail.
Calculator - Calculator - because of dark theme and parentheses on 'regular' mode.
Torrents - LibreTorrent (F-Droid).
Messaging (Signal fork) - Molly.
Manga - Tachiyomi (F-Droid).
VPN (paid, but great for privacy) - Mullvad VPN.
Secondary phone, or any other additional android device (let's say a tablet).
I started partially because of the second, now I'd never go back.
(The main reason was Windows update that made me lose a full month of work.)
OP would lose their data while unlocking the bootloader.
Red-Hat still have an interest to keep it alive, so I still recommend Fedora to people.
It's definitely not in the open-source spirit, but as long as the interest exists, it still a great distro for both newbies and advanced users.
I've found the distro that match my needs, so I won't use Fedora, for that reason.
But it's a closed-source app. You have no idea what it really does, behind the scenes.
(You can google Facebook lawsuits. The number of the results is scary.)
DarkReader is open-source, and on the Firefox recommended extensions list; what are you talking about?