Handling Data with UI, QGIS 3.12

I have tables/layers with hierarchical data in it with and without geo-positions.

Example without:

fid, projectnames <table1>
 -> fk_table1_fid, projectpart, display ... <table2>

Example with:

fid, cable, fk_table2 <table3>

I know I can edit the table1,2,3 by double clicking on a entry in the tableview or by clicking on the feature in map-view.

But for tab 1+2 I do want to have a better workflow/handling. I dream of a GUI where I can add a project and then add parts to it without closing the GUI, open table double click or add… The most important thing I want to have is a much simpler way to use the display-field.
With this field I control the displaying of features in my map. I do want to change it individually on parts-table and for all parts from table1’s projects. (If I click to hide a full project, then all parts have to become false too).

Is this reachable without writing a plugin? I am a noob in Python… I know a little bit about C++ but more with PHP or VB.net.
I tried to make a plugin with plugin builder but it can not found pyrcc5, I installed it resp. There are some .bat with this names on my system, one of this is in %PATH% but it can not be found… at this point I am lost…

Edit: I do want to start editing from a button in a toolbar, or mostly welcome from a dockable GUI/Tab.