It’s still possible to get a chip made, via MPW, from SkyWater.
And you can still use all the open source stuff, like the eFabless pad frame, if you want. But you’ll have to work with SkyWater directly which does require various business agreements to be in place.
Muse semi is an easier path. For Europe there is Europractice which gives access to pretty much any technology.
The problem is access to software and fabs. EDA is expensive and nobody will give access to individuals. Same for fabs. They don't want to give access to a lot of people due to IP theft risks. Anyone can be a North Korean hacker. Plus they operate under US export controls which makes the paperwork daunting.
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.
Most PDKs have an NDA, but Skywater is an exception. Also, most PDKs have some software restrictions on their standard cells because they never tested them with the open-source tools, but with difficulty you can use their design rules in software like MAGIC.
The problem is access to software and fabs. EDA is expensive and nobody will give access to individuals. Same for fabs. They don't want to give access to a lot of people due to IP theft risks. Anyone can be a North Korean hacker. Plus they operate under US export controls which makes the paperwork daunting.