What I'd like is a tool that can be run on a fresh linux install to show what's not working correctly and maybe some diagnostics. Does that exist?

Things like suspend to RAM/disk working, GPU performance is reasonable, WiFi and disk speeds aren't slower than expected.

> Things like suspend to RAM [...] working

If you're on and AMD laptop then suspend to ram can be tested with amd-debug-tools[0].

> WiFi

Here[1] is a list of public iperf3 servers. You can test your connection speed with (change host name and port to appropriate server):

  # Test upload speed
  iperf3 -c host-name-here -p 5201

  # Test download speed
  iperf3 -c host-name-here -p 5201 -R

  iperf3 -s -p 5201

  [0] https://git.kernel.org/pub/scm/linux/kernel/git/superm1/amd-debug-tools.git/about/
  [1] https://iperf.fr/iperf-servers.php