Sorry, but this weird treatment of acme.sh is seriously getting on my nerves. acme.sh questions are certainly welcome here in my opinion and there are many users here who are familiar with it and can help. This isn't a Certbot-only forum.
You can put whatever paths you want; it is totally user-defined.
The idea in the acme.sh --install-cert command is to copy the certificate into a well-known place, chosen by the user.
Loading it from ~/.acme.sh/ is documented to be risky, because the software might one day change the internal structure of that directory.
So, you could just say:
acme.sh --install-cert -d example.com \
--fullchain-file /etc/apache2/fullchain.pem \
--key-file /etc/apache2/privkey.pem \
--reloadcmd "service apache2 force-reload"
and that would be enough. It's not really important whether it goes in /etc/apache2 or somewhere else of your choosing.
What this command won't do is actually configure Apache to use the certificate. You will still need to open up the Apache configuration files and configure the certificate yourself.
https://ssl-config.mozilla.org can help you to find a suitable configuration and, with the example above, the paths you would use are:
SSLCertificateFile /etc/apache2/fullchain.pem
SSLCertificateKeyFile /etc/apache2/privkey.pem