What became of "don't ask to ask" (https://dontasktoask.com/)? Although it may take some getting used to, I find it convincing that one shouldn't need to ask about whether it'd be OK to ask for short questions because the question for permissing is interrupting just as much as the actual question except that with the former it may be impossible to estimate how complex it is whereas it may be much easier to decide if the question is known.

For longer issues, could it make more sense to schedule an (online) meeting?

And on the receiving side of interruptions: Ocasionally it has helped me to just keep the "chat app" closed when I want to concentrate on something. If anyone has something urgent, they could always elevate to performing an old-style synchronous phone call, but interestingly this rarely happens with "text-chat" people :)