Well a small start could be made by scrapping, or at-least postponing, the DCPC periodic training (like that’s likely to happen 
) and telling the DVLA to prioritise the application and renewal of HGV licenses.
It’s not much good creating more tests if new drivers, and not so new drivers, have to wait a couple of months for the return of a HGV licence.
I’m not suggesting this will solve the short term problem but it seems like a good place to start.