You can identify as whatever you would like. There are many sexualities that love non-binary people. Starting off, trans👏 men👏 are👏 men👏, not a separate gender, so keep that in mind. If they do come out as trans, non-binary, genderfluid, or whatever and you still love them, there are possible sexualities you could identify as, such as
Polysexual (three or more genders but not all) (ex. All genders except for girls)
Pansexual (genderblind)
Omnisexual (all genders, not genderblind)
Bisexual (two or more genders)
Also, your sexuality doesn't change based on who you are with. If you are bisexual now, then sometimes people are bi and like nonbinary people too. But if you feel that you are genderblind, then you could identify as pan. If you feel like you love all genders, you could identify as omni. If you feel like you love many genders, you could identify as poly. But also you can identify as bi because these all are under the "more than one gender" umbrella. Whatever makes you comfortable.
And feel free to do research or ask me any questions you have!