The trouble is that the market allocation of funding is dependent on the valuation of goods and services. Until the externalized costs are accurately represented, the market will under-allocate capital toward solving the problem. To push the transition to happen faster without internalizing costs, you'd have to subsidize development with significantly more cash than the market would be willing to allocate with accurately internalized costs. Which I'm not sure is possible.

There are definitely reasons to subsidize some products - medical devices, for instance - as you say, things without readily available alternatives. I'm not writing a detailed transition plan here, just pointing out observations.