Were you planning to keep the 10+ if you get the Note 20+ too??
In your case, having the Note 10 + 5G, adding a Fold 2 would be fun as a novelty item.
If I already had a Note 10 + 5G, I personally wouldn't be that interested in the Note 20+ and wait and be more interested in the Note 21 or 22. The Note 10 and Note 20 would share so many similarities that it just seems to be a waste of money... there is no fun in switching between the two and except for the camera bump no one will know which one you have... if anything they'll think it's a S20 Ultra at first glance.
With that said, even though I find the Fold 2 a interesting novelty item, I personally can't do it either.
It's still too bulky for me to want to carry it in pocket daily. It may be cool for a day to pull it out in public and open it up and browse and the stares you'd get using it, but honestly, I don't need to have people watching what I am doing on screen now that anyone can probably see what I am looking at two/three tables down lol. Also I ride my mountain bike a lot. When I have a marathon I'm wanting to run, I run a lot and don't want to carry such a bulky device and been know to take a spill now and then so now sure how durable the Fold 2 would be and especially if I get sand in my pockets.
My second phone with be smaller and different and unique from the Note 20 in many ways... If I could roll with two phones, my second phone would be a Iphone 12 Pro.
I did put in the 1st post that a condition of getting the Fold was to ALSO keep the Note