[Core Port Req.] JAKKS Pacific plug-and-plays from MAME

Summary

I know that the MAME core for BizHawk currently supports arcade machines only, but... hear me out.

Merits

I think the Jakks Pacific Plug & Plays don't get that much attention. They're like... little arcade machines you can plug in and play on your TV! That should count for something... right? Also it would be pretty funny... right?
Also I just want to TAS the Nicktoons plug n play. I grew up playing this one specifically so I have a special interest in this.

Technical details

MAME added support for some of these systems since 2019 I believe.
Here's a list of some of the plug n plays that currently work fine:
http://adb.arcadeitalia.net/lista_mame.php?game_sourcefile=spg2xx_jakks_gkr.cpp&arcade_only=0&current_version=0
http://adb.arcadeitalia.net/lista_mame.php?game_sourcefile=spg2xx_jakks.cpp&arcade_only=0&current_version=0

The Nicktoons plug n play also lets you insert a Game Key cartridge to access more games (in MAME it uses the default plug n play as the BIOS, and then the Game Key is loaded as a regular ROM.)

Currently the drivers don't support save states in default MAME, so perhaps that could be a problem.

Start by reviewing BizHawk's MAME core integration and the listed MAME driver links for the supported JAKKS Pacific systems. Check how the Nicktoons Game Key cartridge is represented and investigate the stated lack of save-state support. Done would mean a defined, tested port of the requested systems with an agreed solution for save states.