Hadn't heard of a-shell. On my iPad I occasionally use iSH for bittorent, among other uses. I do agree it is on the slower side, but that is in part because of Apple's rules about JITs and this forces iSH to use an interpreter. I do think an interpreter of ARM ISA would potentially be faster as the ISA is fixed width and x86 is not, but I don't know if that would be margin of error faster or not.
Thanks for sharing.
Edit: I may have came across that before, but iSH is more flexible, if much slower.