I am using your programs from long time, for example ZX Spin and principally BASIn, I love to see it in action because ZX Basic was the first language I learned and I think admirable that a language so simple like it can take control of an entire computer, and its users can make games and personal applications with it.
I love your idea of making an OS-like BASIC interpreter. Many had the idea of doing it, but could never complete a project like this, but you seems to know how to continue your trajectory well. Your ideas and features that you add in SpecBAS seems very, very intelligent. I wish you luck with your project!