In my opinion, if they really cared about their stated goals, the EPA should have also rolled right-to-repair protections for the relevant equipment into emissions rules for car manufacturers. They should have mandated interchangeable parts, standard connections, and openly available documentation.
Recently I rebuilt a 1996 car. The previous owner had misplaced a fuel tank topper that contained valving for the emissions controls. The parts needed were simply not available for purchase from the manufacturer or the aftermarket. At the time I couldn't source a used fuel tank for the 96, but I was able to find a 1999 model year of the same car in a junkyard.
Between 1996 and 1999, the fuel vapor emissions controls went from "somewhat complicated" to "really complicated." In theory I should have been able to either hook up just the plumbing needed by the 96 system, or upgrade the whole car to the 99 system. However in practice I could do neither. The fittings had all changed. The charcoal canister was changed from round to square. (And really what is the point of installing either canister when both are probably "used up" at this point? Why can't I buy new canisters at the same stores where I can buy new air filters?)
But the biggest impediment was obtaining information on the two systems. The information in the service manual was perfunctory and nonspecific; multiple different systems had been used in different years and regions. The diagrams of internal valving on the tank toppers small enough that important connections (or lack of them) were obscured by smudges. I had more luck reading EPA whitepapers to at least get a theory of operation.
In the enthusiast community I can find information about how to put a cylinder head from one year of this car onto a block from another. I can even find information about what ports to block off or drill open to remount the cylinder head on BACKWARDS, if I'm so inclined. There's not a similar subcommunity for people trying to repair their emissions equipment.
A similar problem exists with safety equipment. Most enthusiasts of this car just delete their ABS, or they never service it. I want to rebuild mine (this just consists of replacing internal O-rings), but I can't find information or get parts except from overseas. In Europe and other countries that are not the USA, the manufacturer did service and rebuild these ABS units.