SkyWater's 130nm has been used for all (most?) of the Efabless × Google MPW (multi project wafer) runs. That PDK was open sourced as part of that initial effort.

https://www.skywatertechnology.com/first-google-sponsored-mp...

https://github.com/google/skywater-pdk

There's a bunch of other PDKs running around now too. But progress does seem to have distinctly tapered off.