Pixel 6a ~220

PIxel 5a 130

LG has some phones that are also in this price point, but they are carrier dependent like the LG V60.

An old phone has some drawbacks lack they are slower and have less software support but the S10/Note 10 should still be powerful enough for basic tasks for another few years. You just won't be getting any updates on them

Why not get a Pixel? OP 9 Pro has a snapdragon 888, a powerful yet incredibly demanding chip which will lead to overheating and poor battery life. Pixels are known for their custom rom support (where you can flash a custom rom with root access) as well as Graphene OS, ironically the ultimate degoogled android experience.

Price range for used pixels on amazon:

80-120 USD Pixel 4a

90-135 USD Pixel 4a 5g

130-150 USD Pixel 5

130-200 USD Pixel 5a

185-260 USD Pixel 6

210-230 USD Pixel 6a

270-325 USD Pixel 6 pro

You could also get a 7/7 pro, but Best Buy just finished up with a sale for them at 350/600 which is way better than the used market.

Buying the OP 9 Pro would be a huge mistake. If you don't mind a few scratches, the $185 Pixel 6 sounds like way to go, or you can buy the T-mobile variant for cheaper here.