Which plaster is recommended for a double garage?

Hello everyone,
I have a detached double garage with a flat roof. (Concrete ceiling with 2cm PUR and plastic waterproofing). The walls are 24 cm Poroton bricks/high-hole bricks (0.8 or 0.9 raw density).

What would you recommend as a base plaster for exterior and interior? The wholesalers recommended KNAUF LUP 222 (lightweight lime-cement plaster). What do you think? Would it be better to avoid the lightweight aggregate?

Specifically, I cannot recommend any exterior plaster product to you. But before I grant a garage an interior plaster, I would check myself into a mental institution. I can hardly imagine a more shameless cost-cutting measure.

My brick garage has an interior plaster. What else could be a (cheaper) alternative besides a visible shell wall?

My brick garage has an interior plaster. What else could be a (cheaper) alternative besides a visible raw construction wall?

Theoretically limewash or similarly cheap coatings. But practically, a car has no demands to make on the architectural design of its sleeping place (but it is welcome to buy something nicer with its own pocket money). It won't come to that that things start making demands. But not as long as my wallet is still clear-headed.

It is a simple scratch plaster and it was chosen by the GU because it was the cheapest for him to implement. No idea if lime slurry would save anything and how the wall would look in the end with it.

It is a simple scratch render and it was chosen by the main contractor because it was the cheapest for him to implement.

Presumably he did not dare to subject the sacred sheet metal to the raw appearance, or he thought it sounded inelegant in the construction performance description.