An acquaintance of mine had dinner with this couple recently and recommended this post. Thought it might be of interest here. I believe the brand of router they use (Peplink) has a 'Mitigate Bufferbloat' option, but the author does not mention that in the post.
Openmptcprouter took a lot of inspiration from our 2017 work to port mptcp to openwrt.
Mptcp has a mode to duplicate packets over both links, with the slowest one being discarted.
Biggest problem for videoconferencing is to encapsulate udp in TCP.
But i have seen multipath UDP, but never tested any solution.
With 2 links you might have more bandwidth, mptcp first saturate one link before using the second one.
If anyone is interested, i can provide help to make a setup.
Best,