"ZX Spectrum Next" can be adjusted to specification of Spectrum clone machine by TBBlue config menu or dot command.
A video of a demo program for "Pentagon 128" has been posted on official facebook since last month.
https://en.wikipedia.org/wiki/Pentagon_(computer)
By the way, adding TSConf's "Sprite and Tile" screen and two SID Sound to the core of the specification of "ZXSpectrum 128", how many LEs will the core be?

In order to make arcade style games more easily and casually, I came up with another machine as "Option core".

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About rewriting the FPGA
Lately, I opened a "2B board" and started using it as a game machine.
I tried work to upgrade the system core from "1.00.00" to 1.00.10 or 1.00.51. When the "TBBlue" logo mark is displayed, pressing the "U" key on the PS/2 keyboard will bring up a screen to confirm the firmware recorded on the SD card. It took less than 1 minute to erase and update.
Normally, to update "FPGA", create a JIC file or rewrite it using "Quartus" application on Windows PC with USB blaster installed.
On the other hand, "ZXUno" or "TBBlue" will rewrite if you select the core on the flash on the menu screen, and since there is an Anti-brick system, it can be said that renewal of the FPGA is easy.
However, it takes time to update the core "one minute", and it is difficult to explain the Anti-brick system. I think that it is not realistic to distribute the "new machine" in the SD card of the application along with the application.