I use Splore to discover games and my favorites list became very long and unorganized. The work around I found was a short bash/unix command that I saved to a script. It should also work in Windows using WSL or another Linux based terminal. It does not work in PowerShell nor the Windows CMD prompt.

Open your Pico-8 folder that contains the "favourites.txt" file. Normally you can type "folder" in the Pico-8 command prompt and go up a few levels to find it. Then open a terminal there and run:

sort -k 6 -t '|' -o favourites.txt favourites.txt

If anyone knows of a built-in way to sort favorites let me know. My way feels a bit hacky.