Anyone have tips on getting this working with custom images? I tried making my own with TinyEMU and this JsOnline script, but it would never load. Or any sugges

Anyone have tips on getting this working with custom images? I tried making my own with TinyEMU and this JsOnline script, but it would never load. Or any suggestions for another project that fits my use case? That is, presenting a very minimal, in browser only, FULL Linux command line, for training purpose. The image can't be client side, and it has to have all 'expected' functionality; IE, not just a simulator for certain commands/paths.