ZX Next Clones
From SpecNext official Wiki
The core of the Spectrum Next hardware is licensed under the GPL 3 free software license which has enabled the production of several compatible clone machines including:
N-Go - The N-Go is a full ZX Next clone complete with 2 jostick ports, a expansion port and optional custom case.
Xberry Pi - an affordable Next clone with a PCB roughly the same dimensions as a Raspbery Pi 3.
ZX-DOS - FPGA-based hardware recreation of the ZX Spectrum, created by Antonio Villena.