I happen to acquire a Linksys MR6350 recently so I am interested to join the new build test also.
For what is worth: IPQ4019-based WiFi-5 router can still provide decent performance nowadays, able to reach 600 Mbps DL throughput if you have a 1Gbps WAN connection. Not bad at all. If you just want to add another WiFi AP (think like Deco M5) in addition to existing wired/wifi router, this is more than good enough.
We can more or less borrow the information from MR8300 Wiki page, as example, in the 2-step installation procedure. Let me know if I can be of any help.