ARMv7 has been unsupported in GHC for a while. Even the available bindists cause frequent segfaults for compiled programs in my own CI.
Unlike GHC, GHCup has to support historical versions as well, though. So we can’t just go with whatever latest GHC decides.
But I’m not sure I want to invest more time into this. People using ARMv7 could still use an older GHCup.