Released in December 2019, the ZX-ECUTOR interface from Quazar lets you use ZX ROM Cartridges for the ZX Spectrum directly on the SAM Coupe.
Running via the ZX-ECUTOR, the cartridge code can be copied to RAM to run in SAM's fully contended memory so the execution speed is closer to that of the ZX Spectrum, or run directly from the cartridge at an uncontended 6MHz speed.