I'm in Turkiye. The ventilation is good I think, holes aren't small; they are big and I often let the cage get some air while Charlie plays outside.
As for other options, I don't think I ever saw cages big enough for hamsters. That's why I think bins are better. I'll give him some things to climb on in his next cage because he visibly tries to climb while awake.

The size is 40x60 cm which isn't enough, that's why I'm trying to hurry up with the cage change. When I got it, it seemed HUGE to me.
He's always stressful too. I honestly don't know what's up with him, does he need more time before he gets used to me and his environment? He gets treats from my hand and climbs on my hand sometimes, but usually whilst shaking and even bites.