Derived Relations (Formulas)

Related problem
Easy way to demonstrate the need: create a friend list (similar to a Notion template), which helps you staying in touch.
So we have these relations: Name (Text), Last contact (Date), Last contact type (Tag)
I want this table to have different views. I want to show people, that haven’t been contacted in three months if the last contact type was personal OR people that haven’t been contacted in 3 weeks if the last contact was chat.

Another: I have a list of flims with the relations: Title, IMDB score, Rotten score, etc. I want a relation that shows the average score for that film.

The solution I’d like
Add the possibility to create relations based on expressions (like value = AVG(relation1;relation2)).
Add the possibility to use expressions in filters. (like today-last contact < 3 months)

Describe alternatives you’ve considered
No other way found yet.
Sligthly relevant: More robust system for Relations

If this gets a GO, I’m more than happy to help with the ideation from UX perspective.
This expression engine could be utilised for conditional formatting as well.