Could we have a Proton plan that is in-between Mail Plus and Proton Unlimited? We could call it Proton Boost. It would cost $5.99 (or if needed I suppose $6.99).
It would include features of:
+ 1 user
+ 1 custom email domain
+ 10 email aliases/addresses
+ 300 GB of storage
+ Feature access to 15 calendars
+ Feature access to 10 high-speed VPN connections
+ Feature access to Proton Drive (300 GB)
+ Proton Sentinel program

Studying as a student, a plan like thus would be helpful to maintain the privacy needed but also help with the affordability! It also can work as a starter plan before jumping to more expanded plans (with a duo or a family plan).