This is why I think people ending up locked into vendor implementations of passkeys will be a thing. We had a totally open standard, TOTP, and there were still (somewhat successful) efforts make it non-standard like the Symantec VIP Access you mentioned. How many authenticator apps do I have to install? I was hoping for one!

FWIW when I was researching this for my own accounts I believe I saw in passing that someone had figured out a way to extricate the TOTP secret from VIP Access to use in a standard TOTP app. I didn't look into it much though since none of my current accounts require it and it just seemed something to avoid.