[mrob]

>every software/firmware using custom Risc-V instructions is tivoized

I disagree. Tivoization means using hardware restrictions unrelated to the core functionality of the hardware to make it difficult to run modified code. The original Tivo checked digital signatures in the bootloader. This isn't core functionality, because it could be deleted without harming anything.

Merely writing software for unique hardware doesn't count as Tivoization. It's very common for software written for older machines to only run on that exact machine, and nobody calls it Tivoization. There has to be some feature added specifically for the purpose of restricting user freedom.