Strange I hit the 200 product limit on 7.1 so quite surprised when you mentioned 10,000 products. We have a craft shop so we have say a page for wool, a page for needles, another page for patterns. There are certain wool's that go with patterns and equally we need to recommend the correct needles to use. It would be great to be able to able to relate a product from a different store page rather just a random product from the same page that has no relevance.
For example
https://bicesterwools.co.uk/double-knit-patterns/stylecraft-9792
would want
https://bicesterwools.co.uk/double-knit/stylecraft-highland-heather-dk?rq=highland heather
as a related product.
They need to be in 2 different store pages for ease of management and for customers to find exactly what they are looking for.