I've started using indi/ekos/kstars on an RPi and things have been going reasonably well. Thanks!
I would like to better understand the focus tab.

I've been using it to manually focus--e.g. I usually click auto-select star, sub-frame, full-field and then framing.
I look at the plot and hfr number, and turn the focus knob to try and minimze the hfr (ie get the plot points to a minimum).
This seems to work ok, though a little noisy (I assume that's just variation in seeing).

My questions. What do the values on the plot mean? Is this an ensemble hfr or a single star's value?
Even if I try and select the star myself, and view the hfr on the mouse-hint, the values in the hfr text-box and the values on the plot don't seem to correspond to the star I selected.
Or, if I click auto-select-star, also the hfr for that star doesn't seem to correspond to the plot.

Also, is this the recommended way of doing manual focus? Should this work better than trying to center a Bahtinov pattern, or should I just stick to that?

Finally, I'm not sure I understand how to use the relative profile display. What are the two (red and green) plots in there, and how should I interpret the results?

Thanks!

Probably a Bahtinov mask would work better.

So yes this is usually the way to do manual focusing. The relative profile just shows the progression of the star profile relative to the last one. You usually want to see the profile getting thinner or narrower as this means a better focus