Keep in mind though that a fruiting dwarf tree, will likely stop fruiting and start vigorously growing once it own roots negate the dwarfing effect of it’s old rootstock.
This topic has mostly been about apples. And i think quite a few of those can root. And all apple rootstocks i know off can root.
But some other species might not.
And if you burry those to low, you might get rot. and no new roots from the scion to keep the tree alive.