Nils Holm does permacomputing without writting fancy manifestos: https://t3x.org

T3X/0 will assemble binaries for Unix/DOS (maybe Windows) and CP/M.

S9 can do great stuff with very little.

Klong it's a mini APL-like CAS more bound to Statistics than Calculus. No fancy Unicode needed.

Also, Luxferre doing an ultra-minimal numeric VM:

https://codeberg.org/luxferre/mu808

Read the instructions, that mini VM it's surprisingly able.

Finally, Subleq+EForth from https://github.com/howerj/muxleq (muxleq it's just subleq with parallel mux running the exact same intstructions).

From the book you can boostrap EForth from itself with a minimal Subleq DEC file. Enough to run a Sokoban, a calculator (set complex numbers as binomials), and you can implement q+ q- q* q/ to calculate and reduce (lcm/mcm) fractions:

        2 3 1 3 q+  .s 

        3 3 <ok>

        /  . 

        1 <ok>

Luxferre's Scoundrel C port can trivially ported to UXN and even maybe mu808. Eforth for sure, with cells and a minimal 'vector/array/' like implementation.