Remotes: Can a local Drush 8 be used to send commands to a remote Drupal 8.4 site which includes Drush 9?
I would assume install drush 9 locally to a project, but still use alias files for all your remote systems. eg, treat the local installation as a globally installed service conceptually.

if you dont like a random project on your system hosting drush this way stick it on a VM or Container and interact with drush there.