Following up on this, our understanding is that App Clips can run Web Views, so they could run Capacitor apps, in theory. Sounds like the size limit could be an issue, but we are going to be doing more testing to figure out what’s possible here. Any community examples of App Clips running Capacitor apps would be hugely helpful.
In contrast, Widgets do not support web views, and will need to be built natively. It seems possible you could build an abstraction over those widgets to power them through a more cross-platform interface but given the limited size and scope of widgets, it is probably a better option to just add them directly to your Capacitor app and write the relatively small amount of native code needed to integrate with it.