for windows:

• WizTree - Disk space visualizer
• Everything (& EverythingToolbar) - Search tool
• Playnite - Game library

for android:

• Mihon/Tachiyomi - Manga reader
• Obtanium - Manage apps from various sources (github, gitlab, etc)
• Syncthing-Fork - File syncing
• MiXplorer - Feature dense file manager
• Universal Android Debloater Next Generation (technically a windows/linux program) - Remove/disable stock apps

for linux:

• wine/proton - windows translation software
• yazi - File manager
• easyeffects - Audio processing
• mpv - Video player

While the official syncthing-android is no longer being updated, syncthing-fork is still going strong