Having the ability for a mod to add their own tips from their code would be a nice addition, with maybe a config option to disable them if a modpack maker don't want them.

This mod already has support for adding new tips from other mods. If you don't want to hard dep on this mod, they support IMC which you can learn more about here. The key to add a tip is "add_tip".

Of course, you could just access things directly using JustTheTips.tipList.add.