I know you did say you do not want to use zigbee2mqtt, but if you need to buy a hub anyways, why not go direct with a z2m USB coordinator as it opens up your system to many more vendors than just Xiaomi?
Otherwise yes, I also saw that there are problems with this hub, you could check if any of the other hubs support Xiaomi sensors (i.e. IKEA, Tuya).
The issue is, i would need an usb device, and i don’t have an usb device in my Openhab VM so far.
I was not aware that Tradfri supports humidity sensors of Xioami… Because Hue doesn’t as far as i know.
Yes correct, you would need to passthrough the USB device to your VM (I got a separate VM actually for z2mqtt and mqtt running with passthrough on Proxmox). For smaller networks a CC2531 stick works which I did run for a long time, replaced it recently with a zzah stick.
On the other hubs, I am not sure if the IKEA hub supports others, hence referring you to check if some of them do. Personally I try not to use hubs as you are then reliable on those, whereas with z2mqtt you only rely on yourself kind of.
I don’t think I’ve seen anyone use this device with openHAB, but maybe others here have had some success with it. It may also be possible to flash custom firmware on the device Home · AlexxIT/XiaomiGateway3 Wiki · GitHub
I wouldn’t mind one of these devices for the fact it can connect with the Xiaomi Bluetooth devices like the mosquito repellent, which I haven’t seen an implementation for yet. I can confirm that Hue does not work with the sensors, but can’t speak on any other type of hubs. My Xiaomi sensors are running through the Xiaomi Gateway 2 hub which I bought from AliExpress (has to be the Chinese version though) but those are getting rarer to acquire. (The plus side with the Gateway 2 hub is that it has a speaker which can play custom sounds).