if i have admin credentials, and there is no public access to /system, /crx, /apps or anything but /etc and /content, can i install bundles or packages from a public ip using those credentials?
You can create a new user, assigned with username, password, and the ACL rights to write in specific directories within the JCR.
This user can be used to upload and install packages to AEM.
Try using <IP>:<PORT> to bypass dispatcher server and you should be able to perform all activities with admin user
I think, you can't.
1. The post request will be blocked from outside the server.
2. If you can manage to login to crx then you can but you need to access author/publisher.
I would recommend if you have that kind of requirement whitelist your IP to access publisher and you can install package.
but avoid making changes directly on publisher alone deploy the same on the author as well to keep environment sync.