@eylul on a semi-shameless self-plug, I can also reference other projects:

minimalist audio plugin framework, supporting LV2, VST2, VST3, CLAP among other things https://github.com/DISTRHO/DPF

a set of audio plugins created with DPF
https://github.com/DISTRHO/DPF-Plugins

Other generally useful plugins
https://github.com/DISTRHO/Cardinal
https://github.com/DISTRHO/Ildaeil
https://github.com/DISTRHO/PitchTrackingSeries

LV2+Linux audio plugin ports
https://github.com/DISTRHO/DISTRHO-Ports

Plugin host
https://github.com/falkTX/Carla

win/mac cross-compilation
https://github.com/DISTRHO/PawPaw