I am currently experiencing issues using the extensions. After a firefox reboot the browser console shows

The relevant line being No such native application pywalfox

My python version is 3.6.9.

My manifest is located in ~/.mozila/native-messaging-hosts/pywalfox.json and looks like

{
  "name": "pywalfox",
  "description": "Automatically theme firefox using system colors generated by Pywal",
  "path": "/home/james/Pywalfox/daemon/pywalfox.py",
  "type": "stdio",
  "allowed_extensions": [ "pywalfox@frewacom.org" ]
}

I can confirm the pywalfox.py is located in the specified path param. The file has read privileges for all. I have tried to relocate the file to the other specified native manifest locations specified in the moz docs.