Does DDG still have the same upward trend that they used to before Brave caught on?

FreeTube, Invidious, or Rumble.

Not on the same level as SimpleX. With Briar and Session you have you have the same ID for everybody.

For SimpleX you can create a new random ID with each contact, so if you talk with 8 people, SimpleX will create 8 random ID’s and each contact will see you as someone different than how the other contacts see you.

For your hardware setup, I would suggest prioritizing good nVidia driver support over everything. A few distributions do not make the nVidia driver natively available for installation. I expect your Ryzen to be natively supported with 6.1 or 6.2 kernel, but test to see who has the latest nVidia driver to install and thrn decide from there.