Seems like a cool idea, but I can't even complete the first task. The compiler service seems to be broken, since in both lessons and the playground I just get "Could not write source: No space left on device (os error 28)".
RISC-V's instruction encoding is designed to keep the bits of literals in common positions between different instruction types. I believe this is to simplify/speed up instruction decoding. The MSB of the literal is always the MSB of the instruction, which makes sign extension consistent. Most of the other bits in the J-type encoding line up nicely with the I-type or U-type encodings.
This domain was registered today, yet the website claims "10,000+ Apps Created" and lists a copyright date of 2024. None of the links in the site footer work, nor does the "See How It Works" button. There's nothing to show that this site can even do what it claims, and it immediately requests payment without allowing you to verify that any given site will work with it.
Basically, I'm saying that this looks like a simple AI generated scam.