Anyone know anything about disc brakes?

I’ve somehow ended up in a disc brake compatibility fever dream, and wanted to see how others would approach…

I’ve:

• an IS mount older CdF I want to build up for touring
  
• a post mount Ritchey Swiss Cross with older sram rival group/brakes that I want to rebuild with shimano
  
• a complete Ultegra group with BR-R8070 brakes (and bh-90 hose)
  
  

I think my best bet is:

• put the BR-R8070 on the Ritchey with some post to flat adaptors (and look out for GRX derailleur and whatever 11 speed levers)
  
• buy some SLX BR-M7100 on the CdF with IS to post adapter (and work out what I need to make these work with bh90 - hose is long enough already)
  
  

Or

By some second hand hope rx4 as they are pretty

Or

Buy a canyon

Am I missing a more sensible option (apart from buy a more modern frame...)?