Upgrade from 18.04 to 20.04 but retain specific kernel (4.9)

My hardware has a dependency on kernel 4.9 and I would like to upgrade from 18.04 to 20.04. Is it possible to upgrade all the other components without upgrading the kernel?

I found this post that implies (by error) that it can be done.

20.04 retains older 4.15 kernel and radeon drivers. How to upgrade from there?