I have had two wii's for years, but unfortunately I was not really old enough to understand homebrew until around 2013. For years I forgot about the wii until 2017, and finally got into it. I bought another two recently, they are that cheap now. I have only basic C++ knowledge, so far... I want BootMii to work on newer wii's. There is only two possible ways this could occur:
The first one is if the SHA1 hash checking done by boot0 to boot1 is done with strncmp and not memcmp. This would allow for Boot1 to be fakesigned, but really it is very, very, very unlikely that boot0 has this bug.
The second way is by "rewriting" the OTP. The OTP can only be written once, but it should allow erasing data. Erasing data on OTP memory usually results in 00 bits where the data was. If you can find out how data is written, and you erase the bits where the SHA1 hash is; The wii will boot no matter what SHA1 hash boot1 has, meaning you can downgrade or replace it. But usually to protect against further writes, a fuse is blow.
Really it is unlikely BootMii will work in any way on newer wii's, but I shall attempt these two anyway.