Question about the concept of "pilegesh"

Shalom/Salam Cousins (Muslim here).

I have a question regarding the concept of “pilegesh” amongst the ancient Hebrews.

Of course the elephant in the room is the story of Abraham, Hagar, and Sarai. Muslims would maintain that Hagar was a wife (not only based on Islamic tradition but based on the wording in the Tanakh in Bereshit [Genesis] 16:3) though some would say that there were different categories of wives, etc. I guess that’s why I am writing this post, so I digress.

Many people translate the term “pilegesh” as “concubine,” but concubine bears certain other connotations that do not seem to fit based on what I have read. It is also possible that concubinage amongst the Ancient Hebrews (assuming it existed) was different than concubinage in other ancient cultures.

From what I have read, amongst the Ancient Hebrews was “Pilegesh” used for a “wife” who did not undergo a formal Ketubah (marriage contract) process. I suppose a modern day equivalent would be that of a “common law wife”, or someone who is for all intents and purposes, a wife, and recognized by the community as so, but just didn’t undergo this formal process for whatever reason. I mention the community as lay people may not necessarily know who did/did not have a formal marriage, and (especially long ago) perhaps simply assumed the person was married.

On a more technical note – would such a person or their children receive inheritance under Jewish law?

Edit: Removed OT reference.