I've recently released control-components, a C++ library I've been using for most of my embedded projects. It is written in C++17 (with some features from C++20) and uses STL and FreeRTOS under the hood. It contains a lot of building blocks that is commonly used in embedded and IoT projects: finite state machines (FSM), various counters, synchronisation primitives, system loops, sensors, schedulers, HTTP, WiFi, Web GUI, and much more. It also provides GitHub CI workflows for build automation (ccache, various checks).

In general, it's a good starting point for an ESP32 project. It is still low-level, so it can be easily integrated into the existing project. See my another project, https://github.com/open-control-systems/bonsai-firmware - an agro-tech toolkit, for how control-components can be used.

If you find it useful, please let me know!