Migrating from 6P to (non 8.0) phone?

[PGrey]

I'm moving to a Oneplus 5T, the Pixel was just out of budget, and didn't really have the "oomph", even if it was, for me, to pay almost double (for a 128).

Anyway, I'm a bit stuck, I'd really like to migrate my settings and apps over, but I can't get the standard "Setup Nearby Device" to work, or do anything.
It actually completes, if I run it at initial startup of the 5T, but then it doesn't actually transfer anything, at least anything I've found yet.

If I try to run it post-setup, it the two devices won't talk, probably because the 5T is running 7.1 and the 6P - 8.0.

Surely Google thought about this, am I missing something obvious?
I'm 100% on-board with deprecating old stuff that's not useful, but it seems like they should have accounted for 7-8 interchangeability, at least the basics?

TIA, hopefully someone's got some "good news"

 

[revanmj01]

Unfortunately you can’t restore cloud data backup from newer Android version on older one (in this case from 8.0 on 7.x, but same would true with 8.1 and 8.0 respectively).

The only way to restore data in such case is to make backup and restore it with some other tool (like Titanium Backup).

 

[PGrey]

That's really ugly, I mean geez, couldn't they write an XML transform or something, it can't be THAT tough...

I used Helium (had it already from some tablet stuff anyway), but mostly I'd have to say it was a waste of time, it only re-installed a few apps, and maybe a couple of settings in them.

I'm almost back up, but this was a real head-scratcher for me, we're not exactly talking about cutting-edge stuff, some reasonable depth of back-compat.
I miss my WinPhones more every day/week/month ;-]

This means you have to buy at-or-above in your version scheme too, something that's "interestingly challenging", to be nice, in the Android world, eh? ;-]

Edit: Where does it say this, exactly (I'm not challenging the validity, just why it's essentially not documented)? It seems like a weird thing to have be "tribal knowledge".
https://support.google.com/nexus/answer/6073630?hl=en
I'm sure I could find it in a dev-document somewhere, but nothing came up in first few pages when I was searching yesterday, using weighted keywords, etc.