Okay, so my partner and I are both nonbinary and AFAB. I feel like I'm also on the agender spectrum, but as nonbinary gender/s. My partner identifies with gender a lot more than I do.
I personally do not seek HRT. I don't like my body being seen as feminine or masculine; I'm just me. I don't want facial hair, but I want top surgery. I wouldn't mind my voice being slightly lower, but to me, it's not worth the other effects of T. I haven't changed my name or pronouns and currently don't plan to. I do not ever wish to have bottom surgery.
My partner has been on T for a few years now. Like you, they wanted facial hair. They once believed that you could only transition if you wanted to be a man instead. They do not identify with being a man at all. I knew my partner pre-T, and early on in transitioning, they expressed doubts like yours. But after starting T, a primary difference I noticed was how much happier they were as facial hair started to grow and their voice lowered.
It does have emotional and social changes as well. You go through a second puberty, so emotional regulation and thought patterns may change a bit. Socially, it depends who you're with and how accepting they are. We've both had good luck socially with friends, but family can be more difficult. I am not out to my parents; my partner is out.
If the physical changes sound exciting to you, then you probably would be happy with it. If you just want a beard, you can actually temporily go on T then stop. You'd likely mostly keep your beard (it might thin some), but other changes (voice) are also permenant. Some changes are more reversable.
In short, you know yourself best. Take the time and trust what will make you happy. You can transition as much or as little as you want, whenever you want. Start slow. Come out to friends first if that's safer and ask them to call you by your chosen name and pronouns, except around your parents if you want. See how that is in a safe environment first.
Good luck. I hope this helps, and I'd be happy to discuss in further detail via
PM.