Use a One+ 65w Charger?

No , I tried my One Plus 7 mclaren Charger on my Note20U and it doesn't show super fast charging but it will charge it
 
It will work, it probably won't charge at 45W. I'd need it's output specs to be sure though.

Looking at the specs on their (UK) website, it says that it supports PPS up to 45W..
So it *should* work... It won't hurt your phone though, so plug it in and let us know!
 
It will work, it probably won't charge at 45W. I'd need it's output specs to be sure though.

5.0V 3.0A or 10.0V 6.5A (65.0W MAX)

PDO:5.0V 3.0A / 9.0V 3.0A / 12.0V 3.0A / 15.0V 3.0A / 20.0V 2.25A

PPS:3.3-16.0V 3.0A MAX (45.0W MAX)

All Greek to me😁