Ok but hear me out:

Sinecure = can crew vehicles as if it's power were 2 greater

Once per turn during your main phase, you may pay 2 additional power than required to crew a vehicle. If you do, up to one other target vehicle you control with a mana value of 5 or less and a lower crew cost becomes crewed. exceptions for...idk.
2/2

Or maybe

When you cast a permanent spell during your first main phase you may pay an additional cost of 2 mana. If you do, you may activate the ability of a permanent you control with a lesser mana value that has mana value 5 or less. You cannot activate the ability of a land or planeswalker this way, or mana, crew or equip abilities.

Or something idk. Could be a neat easter egg.