You might find https://www.aosabook.org/en/ghc.html https://www.aosabook.org/en/ghc.html interesting, which gives an overview of GHC and the decisions they made

You might find https://www.aosabook.org/en/ghc.html https://www.aosabook.org/en/ghc.html interesting, which gives an overview of GHC and the decisions they made around it. I haven't heard anything about obstacles for high assurance, but the runtime is definitely considered stable, and rarely needs any components updated AFAIK.