Yes, many people can and do add sugar and let the keg sit and carb like they would bottles, then use co2 to pressurize. You'll just want the calculator since you need less sugar when carbing in a keg this way.
British pub style/cask style is where it's naturally carbed and co2 isn't even used for pressurizing, just for equalizing with the pour since it does a gravity draw of the liquid, or uses a hand pump to draw the beer out. Co2 only replaces the space. These are also served at cellar temps (50-60F). There's absolutely nothing wrong with doing those things.
Secondary: GF Czech Lager
Waiting to be kegged, Italian Primitivo
Kegged&Ready: GF Orange&Coriander, GF Honey Lager, GF chocolate ale, GF English ale, Island mist (zinfandel), Island mist (cbry malbec).
Bottled: Infected Mead, Dry Hard ciders, Accidental Sorghumwine, various unnamed.