Heya, Anna,

Apart from the Melio, the better-quality Cybex Mios has one, then all the newer strollers from Nuna, and I also thought of the Polish Espiro Galaxy. Joolz's full-featured models also offer the optional mesh seat as an accessory (but that is no compact stroller, of course). And mltiple brands, e.g. the Britax B-Clever, offer mesh sides, which, however, don't make much of a difference in my opinion.

If I can give you a piece of advice, however, there are also the 3D mesh summer liners that also help air circulation quite a lot - a mesh seatback is not really a necessity. Aeromoov, for example, produces great summer inserts for strollers, and Bugaboo's liners are also very breathable.