then it would be custodial to the browser ?

Is browser local storage persistent? Or would like clearing your cache delete it? So far I'm quite happy with the extension.

It can and does work on snort, the reason that its not recommended is because its not very secure since a lot of sites have been and are vulnerable to XSS

It can, but many prefer to trust one extension rather than multiple websites. Extension has simpler interface too, so less likely to leak due to xss