Do not try and mask this with texture.
I think a skim coat is a DIY friendly project.
Get a bucket of premixed drywall compound and a drywall knife. An 8 incher should work fine. Skim a light layer of compound across the rough spots, then sand it smooth. Shine a bright work light across the surface and it will show you the spots you missed.
This will be dusty, so tape down plastic over everything and wear a respirator.
Pick up a foam sanding block to make the sanding easier: