I think a great next iteration of the simple formulas functionality would be to have them as a relation as well. As simple formulas have now been implemented, it might not be a huge step any longer to implement this specifically as well.
This indirectly partly solves the lack of rollups on Anytype as rollups have frequently been used to do simple calculations. You could attach an object to a collection and add your needed simple formula relations that way.
For example, this is a page from a database I made to show some simple yearly stats of books I’ve read (yes, I’m not a heavy reader, I’m trying my best I swear 
).
I would be able to replicate that on Anytype if this were to be implemented.
Happy to turn this into a separate feature request if needed.