I’ve been looking for the same to no avail. I’d buy one for my MacBook in an instant but the only things available in Germany are bulky hotspot devices with built-in batteries for 300-700€.
I use my phone with an external battery charging it (20800mAh power bank). It's cheaper and more useful to have a power bank than having a dedicated device for hotspot, the same battery can charge my phone, my computer and power any other USB device I might need.
I'm almost sure this is the main reason for these dongles to not really have a market. A phone already provides the same functionality, the battery drain on a laptop would be pretty similar (since the modem on a phone is very well optimised) so extra power through a charger/external battery would be needed anyway if the main issue is draining the phone's battery, it'd just shift to draining the computer's battery.
I'm almost sure this is the main reason for these dongles to not really have a market. A phone already provides the same functionality, the battery drain on a laptop would be pretty similar (since the modem on a phone is very well optimised) so extra power through a charger/external battery would be needed anyway if the main issue is draining the phone's battery, it'd just shift to draining the computer's battery.