Hello,
Hope you are doing well,
I have read the project requirement which you have mentioned here and I would like to give my understanding as what I have understood about the project .
we have migrated more than 10 stores from magento 1.X to 2.X .
we follow the below mentioned procedure:-
1. We check first compatibility of server.
2. We check php version and required extension enabled to run magento 2.
3. We go through the existing magento 1.9.X store and identify if its followed the proper structure of theme or not.
We check if custom functionality is been added and how that custom functionality will be migrated to magento 2.X otherwise it`ll be created again as per magento 2 architecture.
4. We check extensions compatibility:- how many extensions are available in m2, none of extensiosn will work of m1 in upgraded m2 versions.
5. We ensure customer, sales data, products data, category data, tax classes, tax rules migration keeping it on top in mind.
6. deployment of new setup without errors to make it go in live environment.
7. check 2-3 days if any error persists to take immediate action. this is what we ensure and do during a migration.
I hope that I have covered all the important features which you would like to have in your project. However, I miss to mention any point please let me know.
Please come on the chat so i will discuss you more.
I am waiting for your reply.
Thanks
Ravindra.