Here is the s20+ on amazon for $20 more than the s10 lite

https://www.amazon.com/gp/aw/d/B085F3VMT8/ref=ox_sc_act_image_1?smid=A1NX6LTILXOAJO&psc=1

Granted that's the international model and I'm not sure if it'll work BUT there's plenty out there that is the US model.

Definitely consider the A71. There's tons of comparisons on youtube with the A71(&51) vs s20, s10, etc.

If you aren't looking for "top of the line" the a51, pixel 4a and oneplus Nord are also great options. All of these are under $400 and considered top of the line, american, mid rangers

I see that youre currently using the v20... LG phones depreciate in value after like a month so you can snag any of their last gen flagship for insanely cheap. If you're in doubt just call sprint or use online chat to see if the phone will work