PF1e archetypes are similar to subclasses - many functionally are - but are more about using one class as a base and replacing the parts you don't want with parts of other classes you do want. Each archetype is linked to a specific class (which contributed to PF1e's bloat), but you can stack any that don't affect the same class features, and most classes have equivalent archetypes - for example, nearly all the non-companion classes have an archetype to replace something with an animal companion, most of the casters have a martial archetype and the martials a caster archetype etc. You can still multiclass on top and add archetypes to the new class(es), but they're not quite class agnostic so I guess I can see why you wouldn't like them.

PF2es archetypes/dedication feats are fully class agnostic replacements for PF1e archetypes/3.x prestige classes/multiclassing in general - you take them in place of class feats, and have to take a certain number from the same archetype before you can choose a new one. Medic is very popular because feats like battle medicine and ward medic lets any character replace a dedicated healer. Because of PF2es feat-centric design your initial choice of class gives you quite a loose framework of abilities to choose from, which you can then expand with dedications in more agnostic directions, like healing, duel wielding, archaeology, or becoming a lich.