Im not sure that a launcher alone will fix it all.
It will fix 99% of it though.
Even the Google Pixel isn't pure Vanilla Android anymore.
That said, ColorOS (Oppo's version of Android) is very easy to use.
As you said, yeah you swipe up rather than left or right to clear apps, but there's really not a lot to 'learn', and a launcher should fix 99% of this; I think the only difference you'll find after replacing the launcher, is deep inside menus.
Other phones to look into, from reputable brands that are well below $1000 would be:
Almost The entire Nokia series (vanilla Android)
(I actually don't know why anyone who's into touch screen phones would buy anything EXCEPT a nokia at the moment... price to performance? 2nd to none...)
Blackberry (Vanilla Android with a security layer) - (If you want a QWERTY keyboard and Vanilla android; the KeyONE is fucking amazing, been using one since launch day)
Alcatel (has its own launcher, but it's extremely android-esque)
Xiaomi (custom launcher, but less iPhone. Still odd though. But the price is killer.)
Wherever you go in life, watch out for Scythe, the tackling IT support guy.
"I don't care what race you are, not one f*cking bit, if you want to be seen as a good people, you go in there and you f*ck up the people who (unofficially) represent you in a negative light!"