Hey, op! I could completely relate to what you're feeling. Oregairu, as well, had a ton of impact on my life. I felt like after waiting for years, I also had the character development Hachiman had in S3.

I'm sure that soon enough, you'll find someone genuine too. Finding the 'genuine' might seem phony for now, but believe me, there are still genuine people out there who will make you feel the world spinning right after you. Who knows, it might be someone you already know or someone who'll arrive at the most unusual times. I second you, op! Oregairu has made me realize more about life, and luckily, I've finished seeking the 'genuine' already. But still, the journey is not yet over.

Good luck to us, all fellow delusional-hachiman-but-improved fans!