GOROOT_FINAL has some (albeit indirect) effect

It might be indirect enough to be considered no effect. Perhaps the scope of these env vars are vars that can modify cmd/go behavior only after the Go tree has been installed, and cmd/go tests are out of scope. I wasn't sure from the documentation, which is in large part what this issue is about.

Hmm, that's an interesting question. The main purpose of cfg.KnownEnv is to control which variables may be stored (and read) from the go/env configuration file, but today we do not read GOROOT_FINAL from that file:

On the other hand, it really does affect the behavior of cmd/go for all binaries that depend on std, not just during make.bash.

Note that there are a few other environment variables that affect compiler behavior that are also not supported in go/env or tracked as test inputs:

• GO_GCFLAGS (test: doesn't use GO_GCFLAGS for tests #18222)
• GOSSAFUNC, GOSSAHASH (cmd/compile: ssa debug does not regenerate/update ssa.html #31290; see especially cmd/compile: ssa debug does not regenerate/update ssa.html #31290 (comment))
• possiblyGOCLOBBERDEADHASH, and GO_SSA_PHI_LOC_CUTOFF (but I couldn't find any remaining sites in the code that actually consume these variables, so maybe they're gone now).
• GSHS_LOGFILE:
  

  go/src/cmd/compile/internal/ssa/func.go

  Line 734 in 7e71c9c

  if tmpfile := os.Getenv("GSHS_LOGFILE"); tmpfile != "" {

  
  

  go/src/cmd/go/internal/work/exec.go

  Lines 286 to 292 in 567556d

  	if os.Getenv("GSHS_LOGFILE") != "" {
  	// Clumsy hack. Compiler writes to this log file,
  	// so do not allow use of cache at all.
  	// We will still write to the cache but it will be
  	// essentially unfindable.
  	fmt.Fprintf(h, "nocache %d\n", time.Now().UnixNano())
  	}

However, GOROOT_FINAL is somewhat different from those in that it is interpreted directly by cmd/go.

GOROOT_FINAL has been removed following #62047.
Nothing seems left to do to resolve this issue.