Migration can be a complicated process that almost always requires significant web developer expertise. Most extensions have a well-defined process for migrating the content and functionality of your current site to Joomla 4.
If you want to try to do the migration on your own, we can set up a development version of your site on the server where you can work on trying to migrate yourself. The cost for that dev site is $25/month (or $250/year). If you need interGen’s assistance once you get started, we would be happy to help at our hourly development rate of $150/hour.
We provide this information for transparency - we STRONGLY recommend you not attempt the migration without an experienced developer.