Right now I am experimenting with a page for myself, Netlify and an oldschool DNS service, one that does not support ALIAS/ANAME. It’s been a rough ride, and now I’m waiting for “A” record to propagate. Meanwhile, I’ve got an idea - what if there could have been a “fallback” baseurl, in case default resolution fails? I can only guess there could be more applications to this, but also that it might be a bit challenging to generate apropriate “switching” script, that could be useful for cases other than mine.
Closing this thread as off topic.