I know the feeling and you have all my sympathy. It's so frustrating when you don't get any kind of time to yourself.
Dd is now 10 and asd. She has only just starting sleeping (occasionally) before 11. Some nights she still can't sleep until midnight. She gets really upset about it and that makes it worse.
Only in the last 6 months is she ok with me not being in her room. I have slowly (over the 10 years it feels like!) got her accepting me leaving for 'reasons' such as putting the washing away, putting my pjs on etc. all jobs upstairs but not in her room. She can now accept me hanging around in my room and often now is ok with me going downstairs. Though she's not yet able to be comfortable with no one up at all ( can be dh in his office though).
Have you tried a baby monitor so she knows you can hear her? Some are two way do you can also talk to her but my dd doesn't like that as she's worried it will make her jump.
ASMR videos on YouTube can distract my dd sometimes and make her sleepier. Or an audiobook.
Dd hates the 'pressure' of 'time to go to sleep'. So we now just say it's time to rest in bed. She can listen to an audiobook, music, a guided sleep meditation, play with her soft toys, or look at a book.
If I get even a little 'snappy' or force something that she doesn't want/can't deal with, the whole situation is made so much worse and the pressure and stress/anxiety go through the roof. My dd needs to feel totally relaxed and de-stressed. So leaving her when she's not ready would totally make sleep come much later (and sometimes, when I'm tired I do get frustrated. Though it's counterproductive). I'd stop with the leaving her for now until it's done when she's ready to be honest.
Have you tried a bedtime timetable/ schedule. Mine likes to devise and write her own. So with input from me we have, in the past, used that too.
My dd is demand avoidant and we very much have things that work for a while on and off, and then totally don't. So we've had to evolve ideas. Or rotate them. Currently she looks at a book and cycles that with counting to a certain number with her eyes closed, then, if still awake, reading again for a short time.
Good luck anyway! (Written from dd's bed as if she wakes in the night I jump in bed with her as it's the quickest and easiest way for us both to get back to sleep)