In order to build breez you will need to install gomobile and go 1.16.x. If you install go from homebrew, you will have to ensure the GOPATH environment variable is set yourself.
git clone https://github.com/breez/breez.git
go get -d golang.org/x/mobile/cmd/gomobile
go get -d golang.org/x/mobile/cmd/gobind
export PATH=$PATH:$GOPATH/bin
gomobile init
You need to install the ndk as part of your sdk Tools. If you have a separate ndk installed then make sure to set the ANDROID_NDK_HOME environment variable to your ndk install location.
export ANDROID_HOME=<your android sdk directory>
Or in case you want to use a direct ndk path
export ANDROID_NDK_HOME=<your android ndk directory>
If you are using NDK 24+, install NDK r19 and point ANDROID_NDK_HOME to it's folder due to gomobile incompatibility.
Then you ready to run the build:
./build.sh
The file breez.aar will be built in build/android/
./build-ios.sh
The bindings.framework will be built in build/ios/