Supposedly
Garmin offers satellite imagery for plotters with
Navionics Vision+ subscription and downloading via ActiveCaptain, but I haven't played with it myself.
I'm glad I decided to read your link first, before
posting that many have published instructions here for creating "charts from satellite". Since I don't want to fiddle with the
DIY route, I just use the right-click "download satellite chart" option in SEAiq. Toss a coin to your
witcherVenture...
One other thing you mentioned worth calling out is that the purple "fog of war"
Google applies should be considered exactly that: unsurveyed, rather than empty
water. As for the "various solutions" you also listed, to me those are all things the prudent navigator should be doing anyway.