I have created a little system for this, placed directly in the ~.<youragent>/skills folder.

I have a configuration file of marketplaces and other skills to fetch, it can look like. I have my own marketplaces as well, including ones from my company. I use vercel's tool for managing skills with npx, but to easily handle specifically _which_ skills to fetch, the config file is set up as follows:

  SOURCES = {
    'some-marketplace-name': [
        'some-skill',
        'another-skill',
        'yet-another',
    ],
    'https://designsystem.yourcompany.com': [], (empty list: fetch all skills)
  }

from there I simply run "skills.py" (a single helper) to clean/fetch updated versions of the skills.