How do I find a list of products from a given SKU?
You should be able to search for product SKUs by using the free text search query on the list all products end point.
The request would look something like:
where SKUMYSKU is the product SKU you want to search for.
and how to filter multiple products with SKU ? query or comma separated doesnt work
Unfortunately you can not free query more than one string per request. In order to filter multiple SKUs, you will need make multiple requests.