Why don’t you use the Plugin “Kanvas Buddy” by @Kapyia? With it you have color picker, palette, presets, layers and much more available on the canvas, and this even with an interface which is much smaller than the popup palette. By the way, the topic also explains how you can extend the plugin yourself, I think it’s worth reading.
But watch out! If you want to use Kanvas Buddy with Krita 5.x.x you have to adapt it with the patch presented by @SchrodingerCat here.
After installing Kanvas Buddy in Krita and quitting Krita, you have to download the patch, unzip it and apply it. With the files included in the patch archive (kbpresetchooser.py, data. json) you have to overwrite their counterparts in the installed KanvasBuddy directory, which you can find in Krita’s resource subfolder named “pykrita” (on Windows this would be "c:\Users\YOUR-WINDOWS-USERNAME\AppData\Roaming\krita\pykrita\kanvasbuddy", on Linux and macOS you have to adjust the path structure, but it is also there under “…/krita/pykrita/kanvasbuddy/”). After applying the patch, you can start Krita, and KanvasBuddy should work (as before in Krita 4.x.x).
Short version for Krita 5.x.x:
Download and install Kanvas Buddy and quit Krita (download link from GitHub);
Download patch from here (opens Google Drive page with the patch) and unzip;
using your file manager, open the path to Kanvas Buddy in Krita’s resource folder ("…\krita\pykrita\kanvasbuddy" or “…/krita/pykrita/kanvasbuddy/”) and copy the contents of the unzipped archive there, overwriting the existing “kbpresetchooser.py” and “data.json” files;
Done, if you start Krita 5.x.x now Kanvas Buddy works here too.
Michelist
Add: If you are on Windows and can not access your Krita Resource Folder, you have to enable the view of hidden files and folders like in this description: