Miro allows you to draw on the sheet, just like in real life (see video on editing hogwarts sheet here: https://imgur.com/sjqZVxL)
PbtA games don't require complicated automatization, since the character sheet editing is literally about marking and underlining a few dots and words :) For a character sheet to be available in Roll20 it needs to be created and exported there, since it's not available in options (you can check it by "create a game" and "choose character sheet" options in roll20) it's not been exported there. And, frankly, one does not need it :)