Listen, if your kid trusts you enough to ask for a burner, help them. Wipe your old phone or find something cheap, teach them about threat models, private browsing and factory reset, then teach them how to teach these things to other people. The only question you need to ask is, is this for you or for someone else, and you don’t ask who or why.
You don’t need to make the first conversation perfect, you need to make the next conversation possible.
My son recently set up his FOSS phone. I can't give much better detail than that, but those who know will know, and for those who don't - it is not an apple or an android or a windows phone. Nokia doesn't have an OS, right? If they do, it isn't that either.
He has zero log-ins for apps & accounts of any kind (except his mastodon account). He's actually pretty fantastic & groovy, my kid, but also, he's been willing to help others achieve the same!
(1) for most computers, it's not that hard.
(2) and for some it is; I just spent eight hours helping somebody get their refurbished box working. Money, mouth, co-located.
(3) There are often middle-ground solutions for extenuating circumstances, and I do recommend'em when I have specifics enough to do so correctly.
It strikes me as "sanctimonious" to _use that word_ at someone you don't know who is _actually_ trying to make the world better and not just wash my hands of the problem.
I invite you to consider asking questions before resorting to a convenient dismissal.
"(1) for most computers, it's not that hard."
The domestic abuse scenario involves people who do not have control of their own hardware and are at physical risk of immediate violence from the people who do control it. You might as well be telling somebody whose parachute won't open mid-jump that _actually_ replacement parachutes are very affordable.