Looking for recommendation: LTE USB stick for OpenWrt router, Germany

I would be looking for a LTE USB stick supported by OpenWRT, the USB LTE Stick meant to provide the Internet connection, the OpenWRT router meant to provide firewall and WiFi to clients.
I know my way around on the OpenWRT side, but I am basically clueless on LTE support.

I have seen the wiki, but that does not seem to have specific USB LTE stick recommentations. The device list only seems to have all-in-one devices.

Can anyone e.g. name specific LTE usb stick models that are known to work with OpenWRT 21.02?

Or does someone have recommentation, for what to look for, when choosing between available LTE USB sticks?

Or should I rather look for proprietary LTE modem routers and attach the OpenWRT device via LAN?

I use an Alcatel IK40V. When you connect this stick with your OpenWRT router (the repository has all driver needed), you have a new ethernet device, which you can use as your WAN device. Configure it as DHCP client and your router will get an IP address from the stick.

Huawei E3276 or 3372, works really well.

Huawei E3372s-22 here ( europe too ). Work out of the box with any decent router. My setup for years as backup access, now got a B315s-22 bridge mode.

thanks so far

I have not yet decided, currently reading more blogs about the topic: most interesting so far was the blog https://www.lte-anbieter.info/lte-hardware/sticks/lte-stick-uebersicht.php (German)
Outline is: since 2018 no more new LTE USB sticks got introduced, stick development is said to basically be dead. There aren’t even LTE USB Sticks with more recent LTE versions available. Market is said to have shifted to LTE and 5G Wifi routers instead.

E3372s, is available worldwide but as you said they are LTE cat4. E3372h is cheaper ( Hilink mode, but easy to convert to S mode, getting rid of double nat used in H mode ). If you think In future, look at mikrotik products, cat5 cat6 ones, they starting providing 5G modules.
You can connect them to any openwrt based router in bridge mode.

Yes, I've noticed it too - I've been looking for replacements for the cat4 USB LTEs I currently own.
I think I found a cat6 device, but the price was astronomical.

Still the 3372 have been able to deliver 85-90Mbit, which is pretty decent.

Getting/Using an old cell phone, tethered via USB, might be a better idea, if you want to get higher speeds.

Also if you use a tethered phone you can still use minutes of any plan. A problem in the UK with the Huawei routers which helpfully have an RJ11 port like the B818-263 is that UK operators do not allow VoLTE with fixed routers. So drops down to 3G for calls and connection interrupted.