Sure, GrapheneOS is often suggested but Ubuntu Touch is a really interesting alternative, their own store and ecosystem.
The community is amazing and welcoming. If there are Android apps which you can't do without, they can be emulated and used anyway. Imagine switching to Linux and then using Wine for the apps you really still need.
Yes, it's not perfect but Linux isn't either. If you think you're sufficiently tech savvy and want to make a change, give Ubuntu Touch a try. Find a cheap second hand supported device and play around, make some fun apps. (devices currently supported: https://devices.ubuntu-touch.io/ )
To me it's like being back when there was only Windows and Macs as viable home computer OS, and people were getting their feet wet with Linux and all its flavours. Now, it's the same but for mobile.