Limited Channel selection on Orbi RBR50 in AP mode?

I ask this in great frustration: do all the quality mesh systems  take so many channels for their own backhaul - or for any other reason?!

I turned down the radios but then had trouble getting a stable signal when relying on a satelite.

I've spent several hours with my Android running WiFi Analyzer (tried 3 different ones) trying to find a channel that doesn't have "interfence" above 40%, particularly on the 5 GHz band.  This followed my having the sound on Zoom suddenly drop for no apparent reason several times while working today.  I moved the satellite around and did find a spot slightly further from the router where it worked and I seemed to get a slightly stronger signal.  

Using the WiFi Analyzers I discovered there is someone named "hidden" with a signal consistently as strong as mine and often 10 db higher.  I then remembered that someone very recently moved in directly above me and I'll be it's their network.  

I also kept getting an analysis that addressed the level of interference on my chosen channels.  It looks like I can find a place on the 2.4 GHz band away from any very strong signals.  But with the limited choices Orbi offers for 5 GHz, I can't get away from the very clear interference of "hidden",

I also have the guest network turned on.  It often seems stronger than the one I'm using and there doesn't seem to be a way to set the guest to a different channel.

I'm feeling disappointed with the Orbi which was an excellent system until FIOS came into the building, Spectrum increased their speeds and now there are a great number of routers close to me that also have good strong signals.

I don't understand a lot about mesh systems although I know I need one to combat the extremely thick walls.  Might I have to invest in a whole new system?  If so, is there a good mesh system that would give me access to most of the channels?  Or - is there a Netgear solution with my existing devices?

Thanks again.