As a separate note, I don't see how A12 Web (https://www.divergent-desktop.org/blog/2026/01/26/a12web/#a1... ) is different from the current web, where (Javascript) apps are downloaded and run locally (in your web browser) all the time. There are some additional checks for digital signatures and package integrity, which are typically taken care of by HTTPS in the current web.
A12 Web is closer to remote-desktop connection, or a old-style BBS than the current web.
So basically no adblock and no customization unless remote server's owner allows it.