How to correctly implement the editing of site pages on WordPress through the Customize API?

Question

WordPress

Good afternoon. At the moment I use the unison framework with custom blocks on my site, everything works quickly and efficiently, one minus is the visual component of editing, namely the poor interface pic 1. I have already been explained how to edit the site through the Customize API pic. 2, how to implement this question is almost not worth it, the problem is that all data (texts, settings and pictures) are loaded into the wp_option table with the avtoload yes parameter, i.e. data for other pages filled in through Customize will be loaded on all pages, which will become a problem when there are a lot of pages, and therefore data. Essence of the question: Tell me who knows how to implement such editing of the site pages (with such a visual design, namely, the full design of the site, indistinguishable from the original, with pens for editing next to the necessary blocks of fig. 2), i.e. so that it is desirable not to be called all at once, but for each page separately its own settings, perhaps someone knows such a plugin-framework with similar functionality.
figure 1

figure 2