That said, isn’t spellcheck underlining more frequently in the apps you’re typing into rather than the virtual keyboard?

That is something that has always puzzled me, and yes, I believe you’re right.

But, the confusing part for me is, Gboard has a spellcheck option, and if I disable it, it doesn’t underline words when typing (in apps that normally check spelling).

But, let’s take Jerboa for example. It doesn’t work in Jerboa. No matter if enabled or disabled, there is no spellcheck in Jerboa, period.

And that is why things are confusing. Is it the apps that do the spellcheck or the keyboard 🤔.