The game does need a stronghold component, though I’m not entirely sure who you would “buy” the land from, as the land is technically owned by the nobles. Best you could probably get would be to lease the land, which is a similar mechanic I suppose.
Potentially better would be Radzig not formally recognizing you immediately (and he suspiciously doesn’t in the game), and instead you are granted knighthood. Actual knights, not generic men-at-arms, received a knights fie - a portion of land anywhere between 1000 and 5000 acres depending upon the quality. If it was largely forest, it would be the latter, and mostly farmland would be the former. Knights would divvy up this land and have their own villeins work various portions. Those villeins might, depending upon their contract, fight on the side of the knight in his retinue.
Potentially, in that case, Radzig or Divish could give the player control of something like Pribislavitz, and the surrounding woodlands. Henry could spend time and money fixing up the settlement, clearing some forest, curtailing bandit raids (and ultimately crushing their presence in the area), finding people to work the land, and constructing various workshops. For this work, he would get income as well as followers that he could equip and train.