Is there an option to shoot in vlog but monitor in rec709? Probably your peaking will work better then? (am guessing here, no experience with the Panasonic L Mount cameras, but this is how it functions on some other cameras)
Or.... (and I know @MrSMW would HATE this suggestion 😅 but maybe it works for you @Walter H?), shoot vlog but output rec709 over HDMI (am pretty certain the S1 can do this??) then do the peaking with the external monitor (little 3.5" external monitors exist?). That's another process I've heard of people doing to get better results with peaking.
I know the built in photo stacking feature in the Panasonic G9 is very powerful for when doing macro shots and needing more DoF, doesn't the Panasonic S1 have this too? Or is it of no benefit for your style of shooting?