I was wondering if anyone had a way to easily convert an image into a tileset, maybe through a program or something

There's a tool you can use for that: https://hideous-cave-goblin.itch.io/room

It has not been updated for some time, but should work with earliear Bitsy versions.

Possibly pixsy would work too though it’s really intended for photos not pixel art - I can confirm it works well with new bitsy versions tho

https://ruin.itch.io/pixsy