How to migrate products from OpenCart 1.5.6 → 2.1.0.1 or 3.0.2.0?

Question

opencart

Tried several plugins. Products are loaded into the database, they are visible in the admin panel, but are not displayed on the site. The store id was correct. Recommend a free or paid plugin.
A-Migration - Migration of data from opencart 1.5.6 to opencart 2 → products are not shown on the site

Answer 1

Almost any import/export module that works on both 1.5.6 and 2.1.0.1 should work for you.
I usually use this one here CSV Price Pro

Answer 2

CSV Price Pro - does not know how to work with custom tables. All code is closed tightly, so it will not be possible to modify it. If there are none, then you can try.
Look in the official store. There are several modules designed specifically for migrating data between versions.