This solution somehow "merges" the previous approaches; it is based on a small PCB that is used to intercept RGB signals from the A600 Denise chip and deliver them to the Raspbery Pi zero. On its bottom side, the PCB houses a PLCC-52, and on its top side a set of pins for mouting the Denise Amiga adapter PCB that is available on hoglet67 Github page. As suggested, the adapter CLK signal is fed from Denise's 7MHz signal.
This is the PCB stack that enables the HDMI output:
And this is a 3D image from KiCAD:
Final installation on an Amiga 600: