Reddit mentions of The Origins of the Seder

The three best academic books on the Haggadah that I know. All three put the haggadah into it's historical context and try to show it's development based on critical textual readings and historical context.

The origins of the Seder by Baruch Bokser (JTS Press/UC Press)

The JPS Haggadah by Joseph Tabory. (JPS Press).

If you can handle the Hebrew, then The Goldschmidt Haggadah by Daniel Goldschmidt (Mosad Bialik). It was originally written in German in 1936, and this is the Hebrew translation. I do not believe it has ever been translated into English.

As others have mentioned, there was of course the Korban Pesach (with matzot and marror), which was very different from the modern seder.
However, unlike other holidays, whose sacrifices were centralized, national, Temple rituals, Passover had an individual sacrifice -- every family was required to bring its own Paschal lamb. Plus there are the verses about children asking about the holiday and discussing the miraculous redemption. So it's fair to say that there was some sort of home celebration, even in Temple times.

I'm currently reading The Origins of the Seder by Baruch Bokser. It's very academic and a lot of it is over my head, but the general topic is how the Rabbis designed the "modern" Passover practice to give a sense of continuity with Temple practice, emphasizing non-sacrificial aspects of the holiday. Since Passover had these biblically mandated, individual rituals, it was particularly useful for the Rabbis' goal of providing that continuity.