From the TOTP key URI spec, it seems you can prefix the
label field with the issuer in addition to providing the issuer parameter:
We recommend using both an issuer label prefix and an issuer parameter, described below.
to_uri method does not format the
label this way by default if
issuer is set and also actively prevents you from including a
: in the
Happy to submit a PR adding this capability; not sure what the best API is. Additional flag to
to_uri perhaps? Or always including it if
issuer is set?