https://crowselectromusic.com/products/ovum/ is definitely an aluminum PCB - I don't know about any of the others. Plenty of eurorack manufacturers use aluminum PCBs as panels - but keep in mind the printing options are super limited at small scale (e.g. 5 colors for the background soldermask, 2 colors for foreground silkscreen). Using an FR4 PCB has the added benefit that if you leave off soldermask in an area the panel is slightly transparent so you can see LEDs thru it (e.g. http://www.makenoisemusic.com/modules/richter-wogglebug)
https://www.modernsounds.co/pluto https://reverb.com/ca/item/67880740-krischer-micro-3340-anal... https://chompiclub.com/
Another variation is to use a combination of a PCB or metal for the top panel, and wood for the rest of the enclosure. Examples:
https://www.landscape.fm/noon https://crowselectromusic.com/products/ovum/ https://koma-elektronik.com/?product=field-kit