I've been toying around with this idea, but hypothetically, if you had a password manager that would use any possible renderable (e.g. not control characters such as BEL, NUL, DEL, etc., or surrogate characters) Unicode code points, and a site backend and hashing algorithm that would accept them, how many bits of entropy would a sixteen character password provide?
I'm not 100% sure I'm calculating this correctly, but according to this StackOverflow answer, there are 1,111,998 possible valid code points for this purpose, so each character should provide
log2(1111998) ≈ 20 bits of entropy per character, correct?
Would this break any common password hashing algorithms such as bcrypt? Are there any unforseen problems in using unassigned unicode code points in passwords, save for some sites restricting the character set available to use?