Understood about Pandora v. Toy Story Land. We were at Pandora during Opening Day; even with the extended hours (until 1:00 a.m.), you're right, they were not "walk-ons." In comparison, TSL went much better -- yes, there were people, but at under ten minutes, I'd argue that's effectively a walk-on, LOL. Also, most importantly, we weren't in TSL until December, so, by the time we got there and bought the After Hours tickets, TSL had been open a reasonable amount of time (although it was still packed during the day -- the factor that convinced us to get the AH tickets).
Given the INSANE crowd levels expected for Galaxy's Edge, there will ABSOLUTELY not be any "walk-on" rides; perhaps what's more likely is a "short" wait of 60-90 minutes. Still and all, I'd go for it.