alright I just went through the upgrade.
my situation: I set one up a long time ago, not really remembering what exactly I had done.
research: I knew how to use the terminal and git. pulled changes from upstream
git remote add template https://api.glitch.com/git/glitch-in-bio
git fetch template main:main
git log --oneline --graph --branches --decorate
git diff main...
my starting point had been from d67c3727085eb360b725e4a126c3808e83cf8088 (private github link if anyone reading is on the glitch team 
), which is somewhere circa Version 0.0.2.
I had edited index.html, the “gallery” theme css, and filled in links in the settings.json
updating:
git merge main
conflicts in index.html and settings.json
index.html: seems pretty darned different. I only added on <script> tag, so I accepted changes from main and pasted my tag back in
settings.json: conflicts in links array and conflicts in social map
links: img fields are all annoyingly marked as changed in main due to added space in "img":"https://..." → "img": "https://...". I hate how much trouble this created.
social: at some point in time, the map got sorted, which created huge conflicts. I hate how much trouble this created too.
and then I found out after resolving these conflicts that Glitch had automatically committed stuff in the middle 
so it became total chaos
and some extra feedback, my bio page now has a service worker, but I’m opposed to every stupid webpage having a service worker 
kind of an un-delightful experience, sorry to say 
