https://www.youtube.com/watch?v=DFnP5TK61aI
https://marginalrevolution.com/marginalrevolution/2020/04/wh...
http://www.overcomingbias.com/2020/04/reply-to-cowen-on-vari...
I know your proposal is not exactly that, but it has some overlap with those ideas. I'd recommend joining those discussions on those blogs.
If yours significantly improved the safety of their proposals, it would be a welcome addition to those discussions.
Note though that it shares some obstacles with widespread vaccinations, in that safety and efficacy testing is the major delay, not the chemistry.
We could alternatively do low dose variolation on the young with technology today, with infectious strains administered through a cut on the shin to encourage lower severity progression. We might lack implementation capacity and social will to try very experimental approaches. If so, "found strain" vaccination will face similar capacity issues while also introducing new questions about safety and effectiveness and requiring significantly more research.
So I'm not sure it's a silver bullet, or how it fares against existing proposals, but seems an avenue worth exploring in parallel, and raising first with others generating policy ideas in this space.
N.b.- Tyler Cowen has a foundation that is actively providing grants or prizes for work on COVID-19, he's not Gates, but not just some random blogger either.