A small but relevant part of the story:
Discussion
A "pretty OK" recently-written book on it:
Robert McKenzie, [Identifying the Seed: An Examination and Evaluation of the Differences between Dispensationalism and Covenant Theology](https://a.co/d/76C9Lxc)
Best thing to read "contra" it would be, in my opinion, -- Paul's Epistles. Especially Galatians.
Thanks for sharing all this! I understand a lot better now, especially the Biblical and modern historical context.