Does not help you but the question nerd sniped me to try it as an exercise in my preferred tiling WM spectrwm.

https://github.com/conformal/spectrwm

This lets it act as a sort of toolbar, present on all workspaces.

in .spectrwmrc add

    #shrink the region by 112 to allow space for the widget
    region = screen[1]:2448x1440+0+0
    #add quirk to remove from normal workspaces
    quirk[Gkrellm] = WS[-1]

then start on right side of screen

    gkrellm -geometry -0+0

I normally would probably just put that in my .xsession but there is an option to auto start it with spectrwm, untested

    autorun = ws[-1]:gkrellm -geometry -0+0