This description is still a mix of various features, without explaining the WHYs good enough.
What I believe you mean
1/ Transfer to other computer
Not needed, your private templates are stored in our database and linked to your account
2/ Sharing private templates with (few) others
Better explanation of the use case here
3/ Backup
Not needed, AIPRM performs backup
4/ Forking of Prompts to Private?
Read this
Fork a public prompt to a private prompt
5/ Editing in source format? With revisioning in GIT?
Developers may like this, normal users consider markdown a “programming language” already (see Export ChatGPT output as PDF or DOC )
Defining and coding an import/export format is a huge undertaking if you take the biggest problem into account - humans editing that.
100s of potential syntax errors need to be handled ,
AND supported (for years!!) and of course “I did it right, the software is broken” is the typical response from users unable to flow even trivial instructions, let alone the syntax of an export format.
We supported 1000s of customers who were unable to provide a CSV file with 2 columns correct, with example CSV file given. “Technical” SEO people, 
No thanks, that kind of support headache will not happen in AIPRM.
So I don’t know why we should do all that, and for whom of the 600,000 users and WHY.
Only a few 1000 are using Private Prompts anyways. Will they pay for all this (support) hassle? I am not sure.