Then we could possibly have new, from-scratch, independent browser engines that could compete with the status quo.
We did have a technology for adding interactive app-like content to hypertext documents, it was called Flash. I do hope that it gets eventually resurrected but as an open standard. There is an open-source Flash player being actively developed right now, Ruffle. There isn't an open-source authoring program yet, but this feels like a much lesser issue. IMO it's important for there to be that boundary between the "document" and the "app". The only real shortcoming of the original Flash was that it relied on a proprietary plugin.
Of course, Apple also needs to be forced to allow app sideloading, that's regardless of what they do or do not implement in Safari.
No more porn. No more innovative experiments. No more kids making dumb little things to learn programming. No more freedom to set your own app policies.
The web is the only platform keeping user and dev freedom alive and it's imperative that hackers like us fight for it.
The following things have been pushed and enabled by a single web ad agency with complete disregard to concerns and objections: WebUSB, WebBluetooth, WebSerial, WebMIDI. There are countless others.
The web hasn't been neutral for a very long time. Google believes the web is it's own playground now.