according to https://gist.github.com/XVilka/8346728 terminal programs with libvte >= to 0.36 can have 24bit true color support. My preferred terminal is xfce4-terminal... I haven't found another terminal with the features it has.
It would probably be easiest to have a repository to download it from.
Failing that, I have the newest version of libvte (.39) and xfce terminal (.63) source code and have been trying to figure out how to compile it without borking my ststem, but libvte wants a newer gnutls, which requires an older libnettle then ubuntu/linux mint has, which requires uninstalling libnettle4, which removes cmake and a bunch of other programs, and this seems like a horrible way to go, and that's not even the end of it. Plus all the source compiled stuff then doesn't get updates.
I guess I would also be okay with someone pointing me towards how to build all if it in something like a docker container or VM, and then using that. It's possible though that libvte needs to be linked against, in which case I'm not sure a VM will do it.