There doesn't seem to be.

I only heard if you unlock some class called chemist though not sure if that is what it was called

This is correct, there is only one class that can use items during battle. The idea behind it was to have magic-based classes able to deal more damage in a short amount of time with the downside being that they eventually run out of MP, whereas physical-based classes typically deal less damage in the same amount of time but can keep going indefinitely.

Refilling MP between battles can be annoying (especially late-game), so I did add the Auto Top Up option that can be used to do so quickly, and it can be favourited for fast access in the Favourites/Quick Menu. This might not always be the best option when money is tighter in the early game, though.