Some require a party, but i as a warlock with hireling and strategy managed to solo some of the "extremely challenging" dsungeons. The solo friendness depends a lot on the class and build. In general, divine casters with fighting capabilities are the most solo friendly classes...
Keep in mind that certain Origin stories are closely intertwined with their characters' respective classes. If you’re opting for a non-cleric Shadowheart or a Wyll without his warlock pact, this will undoubtedly influence your roleplay options in dialogues and the overall narrative for these ...