I agree with @bofh00, some sites do have arbitrary “special character” requirements that force users to use at least one symbol out of a specified set that doesn’t match Bitwarden’s. For these I have to generate a password, copy to a text editor, make arbitrary replacements, then paste the modified string. I can also go to https://passwordsgenerator.net/plus/ which gives me the option to edit the list of additional characters.
It would be nice to be able to do this within Bitwarden’s generator. I like @hoyolo’s mockup above; minimalist but effective.