It’s a great idea, but don’t judge the interest by the relatively small amount of installers that will comment on your post!
“Build it, and they will come!”
The industry desperately needs it as it has a greater opportunity for ‘cowboys’ than ‘double glazing’. With the latter you must have at the very least watched someone else have a go, but anyone can pick up a saw, hammer and a piece of decking. That doesn’t mean to say that decking is easy, but it does show that the industry is more likely to have a higher number of ‘cowboys’ than the ‘replacement window’ industry – because they do have minimum standards to meet via training or APL.
For me personally, I would be interested in the design side but the ‘old back’ couldn’t do anymore fixing.
Go for it! You have my full support for what it is worth.