I'm no expert on LTE but the Teltonika 955 is only CAT4 and limited to 150Mbit/s isn't there merit in getting a higher spec proprietary LTE router/modem and placing in bridge mode (or equivalent) and coupling to an OpenWrt router? For example the B818-263 is CAT19 and offers features that in the right conditions will give very high throughput.
I'm open minded - if there's a better product out there than the B818-263 or particular benefit in having OpenWrt on router w/ modem then I will switch over.
B818-263 seems like to option for me... seems for me too big and i want to built the router inside a device....
Teltonika 955 seems OK, but if it´s not working with Open Wrt it´s for me a show stopper...