Yes, it's required for life, in theory. Some women apparently do give up dilating after many years and suffer no ill effects, but that's never guaranteed. Yes, it is also possible for the vaginal canal to heal closed, though I think it's more common to simply lose depth to the point that it's basically just a "dimple" instead of a vagina. However, that's more likely early on; by a few months post-op most people have a better sense of their own body, and how long they can put off dilation in an emergency, etc.
However, by two years post-op I was down to once a week for 15 minutes, which isn't bad. I spend a lot more time doing the dishes.

I'm fairly sure that by now I could wait a bit longer than that, if I really needed to - so if I were spending, say, 10 days as a houseguest, I'd probably leave the dilators home. (But if you don't, hey, plenty of women *do* travel with discreet sex toys...) I'm happy to answer any other questions you have, too, because you're right that the info out there intended for cis people is woefully incomplete for us.
Every surgeon's dilation schedule is different, though. I hear Bowers requires daily dilation forever, for example.