Best practice for deployment with pipelines using Bitbucket?

Question

We're a small IT company and make websites for our customers, which we maintain using Git via Bitbucket.

I would like to know what the best practice is for deploying code using pipelines via Bitbucket, since we are now logging on to the server using SSH and run the following commands for deploying:

• git fetch
• git pull

While the desired situation is to do this using pipelines.

I'm also wondering how this would deal with merge conflicts if the customers change the code on their end using FTP. Should they get their own branch?