Their are cheap adapters available online, including Amazon, to allow a non-disc frame to mount disc brakes. You could try ordering one of those and a disc-ready fork, then find disc-ready wheels.
Disclaimer - My only foray into this is ordering an adapter off Wish. I have yet to install it and will probably have my son weld it to the frame when I do. And it's for a beach cruiser, so I don't plan to put any real stress on it.