MacOS – ssh -A doesn’t properly enable forwarding of authentication agent connection

Bash has special provisions in its source code to source ~/.bashrc when it's invoked by rshd or sshd. It's a compilation option, which given your experience seems not to be turned on under OSX.

If you're logging in with a key, you can (ab)use the command= option in the ~/.ssh/authorized_keys file. A key with a command option is good only for running the specified command; but the command in the authorized_keys file runs with the environment variable SSH_ORIGINAL_COMMAND set to the command the user specified (empty for interactive sessions). So you can use something like this in ~/.ssh/authorized_keys (of course, it won't apply if you don't use this key to authenticate):

command=". ~/.profile;
         if [ -n \"$SSH_ORIGINAL_COMMAND\" ]; then
           eval \"$SSH_ORIGINAL_COMMAND\";
         else exec \"$SHELL\"; fi" ssh-rsa …

Note that I put line breaks above for legibility, but this actually needs to be all on one line.

How can I set environment variables for a remote rsync process? may have other helpful suggestions.

When you initiate port forwarding, you don't specify the user.

localhost:~ user2$ ssh -L 8022:server2:22 user1@server1

You need to specify user in the second command:

localhost:~ user1$ scp -P 8022 user1@0.0.0.0:file .

That should work fine for you