Yes, you will see results after one session. Should, at least. If you don't, then maybe they were overly cautious with the machine's settings for a first time. But it probably won't be miraculous. Some lucky people are done in 5 sessions to be done, but some unlucky ones need 15, maybe even more.
But yes, plucking is a problem. In the long term it probably doesn't have any noticeable effect. However you MUST stop plucking at least a month, ideally 6-8 weeks, before your first treatment, and stop plucking altogether from that moment onwards. Every hair that you pluck, you essentially save it from possibly being destroyed by the next treatment. Yes, it means it's back to shaving for 6 months or more for you. Yes, that's why it's a good idea to start laser before transitioning. Yes, it'll be hard. Sorry, but if you want to be done with facial hair, you have to stop plucking it. Even if you do electrolysis, plucking isn't exactly advisable.
Also, at-home permanent hair removal... In the laser and IPL area, it's likely that the machine won't be powerful enough to kill everything. Might work though. Well, it WILL probably work, at least partially. As for electrolysis... don't. Not everyone has the required dexterity to ever hope to be able to do electrolysis one day, no matter the training. And you need professional training or you'll put your skin in danger and not be as effective as you could be. And most importantly, doing it on yourself, even on a leg, is a lot more difficult. Imagine in your face, in a mirror, struggling with direction reversal.