I don’t know if there any which could be Pro-type features.
I’ve made a few product enhancement suggestions on the forum over the last few weeks. These are the only things I can think of that I would like to see in Emma that aren’t currently available or are currently limited in some way. But I suspect none of these are Pro-type features.
In some kind of order of desirability:
Accounts tab organisation and sorting
Better search
Editing pending transactions
Better/user-assisted transaction linking
Link to merchant search from within transactions
Feedback on logo submissions
Support for 3rd party keyboards
Some for-profit companies do it. For example, The Guardian newspaper has a Contributor option which allows you to contribute as little as £1 either as a one-off or regular payment and is independent of their Premium subscription tiers.