There is indeed an “edit context,” a restriction of which layers a plugin can edit. This usually means that a plugin can only edit selected layers and layers “close” to it (within the layer hierarchy).
Unfortunately, there are some edge cases there when it comes to components (formerly symbols). This (as it is right now) can prohibit plugins to edit contents of component layers, unfortunately.
It kind of depends on what you mean by “search”. The editing context only restricts editing the layer, “finding” it should be possible for plugins.
Unfortunately, there are also some restrictions on how plugins can interact with components within a document. As far as I’m aware, there’s currently no way for plugins to determine or manipulate the different states a component can have, manipulate, or “view” the list of components available in the assets panel, and so on. The APIs still need to catch up in this regard.
All in all, there are indeed some restrictions in this regard. Still, it really depends on what you need to do (just “searching through and viewing” shouldn’t be a problem if you don’t need more detailed information about the component’s “inner workings”). Also, manipulating content within components can be a problem (without, as far as I’m aware, any workarounds).
All in all, the plugin developer community is very much looking forward to ways to get around these restrictions, but “by itself”, the “editing layers inside a component problem” is real, so to speak.
I hope this helps,