As @g-andresen pointed out, there is a potential solution using my custom threads app and ThreadKeeper. Even though I'm a team of one I do store my custom thread files in the cloud (Google Drive in this case) so I can use my backup laptop if need be and still have access to my custom threads.
Prompted by your enquiry I wondered whether I could use the AutoDesk Desktop Connector software to store my custom thread files in (if you don't already know this gives you a 'Fusion 360' drive that reflects your Fusion data panel). I created a new project called Custom Thread Files and copied all of my custom thread files to it.

This might be easier to manage than yet another cloud service as far as team access goes. However, there appears to be an issue with ThreadKeeper syncing when using this particular cloud solution. I had it work with a few sample files but when I tried to sync all my files it errored out. My app does have a syncing facility but it's not as automated as ThreadKeeper. There has been mention in the past about changing the location of thread files so that they sync across the team and also don't get moved with every Fusion update! The 'Assets' folder has been suggested IIRC.
Anyway, I hope this helps.
If this answers your question please mark the thread as solved as it can help others find solutions in the future.
Marcus Wakefield
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I've created a Windows application for creating custom thread files for Fusion. You can find out about it here. Hope you find it useful.___________________________________________________________________________________________________________