Choosing a free CMS for market place - which ones to watch?

Question

CMS

Advise market place designers. We know about Bitrix.
How will they be used?
Suppose a person has a desire to collect in one place all baby carriages from different online stores and live from transitions to donor sites. Moreover, in one case, each online store in this constructor has a personal account where they can keep the content up to date, and in the other case, the content will be kept up to date by the constructor operator. Similar to market.yandex.ru
What comes to mind?

Answer 1

Too specific task, besides, if your constructor does not accept files in Yandex format (Yandex market), then no one will monitor the relevance of the information with pens. Now there are quite a few such sites, but they are all self-written.

Answer 2

Why are there no ready-made solutions? what is specific?
Found hints from correspondence. They advised to watch CS-cart multivendor and catalog.savgroup.ru
But the first one is paid, and the second one is frightening with its specificity, which grows from the cataloger's windows engine.
Is it possible to teach opencart to work with personal accounts? Or what else would you like to see? Very important - flexible categorization (with tags) and search-comparison of goods.