Just caught that discussion but honestly trying to learn nollie flips out of a quarter sounds crazy to me (but it might work for you, everyone is different, who knows), I feel like transition throws off all the physics of that trick. Switch flips on a bank might be a good idea though, if anything to transition in between flatground switch flip to flatground nollie flip or the other way around depending on which one you learn first.
Frontside nollie flip thing is funny because it used to be true for me too but I wouldn't necessarily recommend it personally (but it's still a possibility), it's quite easy to mob the fuck out of those first frontside nollie flips and get used to bad technique even for straight nollie flips in the end. Funnily enough the 180 ones now feel a lot harder to me too, but that's because I actually try to pop and form them right which I couldn't do back then (and is also why I stopped doing that trick, at least my mobbed ones felt like shit). For nollie flips the key is to use the forward momentum to push ahead of you on the pop (off the big toe) and jump what feels like backwards (towards the tail) all the while really bringing the board with you for the flip, really like a straight nollie but with insistence on your toes and then at the peak you flick out, shoulders aligned the whole time. I say it all the time but it's also a lot easier to learn switch flips by pretending you're in your regular stance and it's your normal every day kickflip that you're trying to fix, forget you're doing anything different and it will kill the whole mental block of a myth around the trick. Sorry to hear about your ankle, be well soon.