Dear Client,
My Name is Ananta, from EWall. I have read your description for Magento1 to 2 migration.
These are my inputs based on our experience:
1) Need to migrate only absolutely needed data, like customers, products..etc. need to avoid migrating older orders or anything related to calculations, dates or pulling data from various models. This will help the site be bug-free and free from unnecessary data dump.
2) Migrating extensions are next to impossible, you have to look for related extensions, thus we need to avoid migrating past extensions data as well. So we cannnot striclty have a copy to copy.
3) Again, we need to have a open approach for customizations as well, for this you have to provide the details how much customization needed.
4) This project need to be agile and must have hourly budgets otherwise it will be difficult to execute as migration is highly challenging, time-consuming, especially considering your 20 + domains.
5) Migration of selected data happens multiple times over a period of time to test its integrity.
My bid is only a placeholder and the actual budget will be given after checking all the details like the size of the data, the number of extensions that need to be installed, and customization requirements.
We provide consulting, development and customizations using M2 CE and EE editions. Please reach us to discuss your requirement in detail.
Kind Regards
Ananta