Sure
M2 was shopped around and ALMOST sold to Sega in 96, but ended up going to Matsushita / Panasonic. They hyped the hardware but kept pushing the release further and further back to "Ready" it for launch.
A combination of things happened that killed M2. One) Panasonic got a new CEO who wasn't dedicated to M2 Two) They felt competing against Nintendo would be difficult in Japan and Three) Dreamcast was on the horizon and M2 couldn't keep up. Had it released it would have been the dominant platform for maybe 18 months before it too was "obsolete".
As far as what hardware goes for its a major range. Thousands though now. Arcade hardware goes cheaper but will not play demos such as these, as while the hardware is identical, the BIOS file are not. I am always working on fixing this but its a massive project
As far as how much software exists ; five full arcade releases by Konami. On the "home hardware" front, IMSA, Ironblood, multiple demos, and a game/demo called "Dolphin". That's the only piece of software I have not acquired.
I will be showing more in the upcoming months, as I have collected probably too much stuff for M2 lol. Running out of physical space to house it all!