Hey Hana – I love what you're doing with in-app. Congrats on YC!
Courier (https://www.courier.com) is also in this space, but we're focused on other channels like email, Slack, SMS, MS Teams, SMS, etc. as well as handling orchestration capabilities around lists, preferences, and sequences. I'm pretty confident you & I started Magicbell & Courier for the same reason: we were both tired of seeing this have to be built over and over.
Glad to see the space is heating up!