I haven't been badge hunting but checked the Zwift (in game) badge page and then the ZwiftInsider
Routes by Difficulty page. So, I did the shorter easier "1 Bidon" ones I was missing just to fill in the blanks and now all I have left is some short steep segments and those longer ones like the PRLs and various Pretzels. - what the list calls 3, 4 or 5 Bidon routes.
My longest ride so far on Zwift has been 2 hours or so, and that stretched my enjoyment limit for cycling in the basement. My wife is going away for several weeks, in February, I'll have time to kill - may try one of the longer ones with a break at the 2 hour point and see how it feels.