Squidman, iOS devices, SSL and Docker
I solved it using this Docker container:
https://github.com/jpillora/docker-dnsmasq

Simply follow the instructions and add e.g. 127.0.0.1 app.dev and 127.0.0.1 api.dev to your /etc/hosts.

Then change the DNS on the macOS and iOS device to 192.168.178.64 (following the initial question).