If you can run ITER for 20 minutes you've essentially proved the Tokamak concept is viable for commercial use.

No you don't. Commercial use means it makes economical sense. When you have to spend more on maintainance (and recycling/dumping contaminated wall material amd somehow get the fuel) then you never can hope to make any profit.

A running ITER with positive energy output for 20 minutes just proofs that the concept can actually work. From there to commercial use would still be a long way, if it ever can compete at all, except in niches, like deep space.

(I rather would bet on the Stelleratar design)