It's incredibly easy to make an adapter. You really only need the female DVI and ADC ports (you could probably sacrifice a few cables if you can't get the connectors, too), a breadboard and some wire. https://lookanotherblog.com/diy-adc-adapter/
the adapter is passive since both connectors use the same signaling protocol
the problem is that designing tooling to manufacture a custom connector at scale is expensive, so nobody is going to do that until they know there is enough demand to at least cover the upfront cost of designing that tooling and manufacturing a bunch of these.
If the demand is low enough to not even bother stocking them anymore, it would seem like someone could offer to sell them on Etsy or something, doesn't seem to require much much tooling.
If it were, they'd likely be expired by now.
I wonder if an adapter could be made some "DIY" way, if it needs to be active, it could be a fun project for someone into FPGAs.
It's incredibly easy to make an adapter. You really only need the female DVI and ADC ports (you could probably sacrifice a few cables if you can't get the connectors, too), a breadboard and some wire. https://lookanotherblog.com/diy-adc-adapter/
the adapter is passive since both connectors use the same signaling protocol
the problem is that designing tooling to manufacture a custom connector at scale is expensive, so nobody is going to do that until they know there is enough demand to at least cover the upfront cost of designing that tooling and manufacturing a bunch of these.
I didn't notice at first, the article itself links to a seemingly easy way of making a DIY adapter:
http://damntechnology.blogspot.com/2009/02/hacking-dvi-cable-to-build-adc-to-dvi.html
If the demand is low enough to not even bother stocking them anymore, it would seem like someone could offer to sell them on Etsy or something, doesn't seem to require much much tooling.