Can I use an 11-32 cassette promoted for MTBs on my trekking bike with Shimano Acera rear derailleur? I need to replace my cassette but assortment is restricted atm. Can I use the following cassette on my bike? < It's an SRAM PG-950, 9 speed, 11-32T. With regard to those numbers it should be fine on my trekking bike. But what confuses me is that it is explicitely promoted for MTBs. Is that a deal-breaker or irrelevant?

All common 9 speed cassettes use the same freehub body. Also, trekking bikes normally use MTB parts, so there is no problem there. The Acera line is an MTB line. The manufacturers normally only distinguish (with some exceptions) road/MTB/urban and other bikes like hybrid, trekking, gravel, cyclocross take many components from those lines with only a few specifics.

Just check that your Acera rear derailleur actually allows this 11/32 range, but it should. All should be OK.