I am currently using a Mikrotik SXT LTE (https://mikrotik.com/product/sxt_lte_kit_us) for internet connectivity. I would like to upgrade to a pair of these devices and load balance them through pfSense to double my internet connectivity. To do that, I believe my best option is to put the SXT into a bridge mode. Unfortunately, Mikrotik RouterOS doesn't support that option on this hardware so I'm trying to find out if OpenWRT will support it.
My first question is if my plan seems feasible or if there is an easier way that anyone can suggest to me?
Second question is if someone can point me to some docs on bridge mode compatibility on OpenWRT? Or for that matter if someone has done anything like this?
You should be able to do this with the stock firmware. Configure them so that the IP you get from each one is in a different subnet. Then load balance the two "WAN"s.
This is double-NATting, which is fine if you're not accepting incoming connections. Most phone companies NAT LTE users through private IPs in their equipment anyway.