Good practices or best way to parallelize automated tests [Selenium + Java + TestNG]

What is the best way to parallelize a test suite execution, either in graphical interface or in Headless mode? Currently I do it this way:

• I have 3 Jobs at Jenkins. Each Job runs a different suite.
• In each Job I connect to a remote machine by SSH, and there I execute a bunch of commands (mainly to run scripts and Docker commands).
• For each Job I have 2 containers, one to run the RemoteWebDriver (selenium/standalone-chrome) and another one that is the one that contains the Maven/Java automation project.
• At the end of each execution, a report (Extent Report) is generated for each Job and I copy each one to an Apache server located on the same remote machine (outside the container).

Obviously I am not even close to be an expert on the subject. I have been working in this sector for a short time and I am still learning things.

I tried to do it with TestNG, but there were conflicts with the PageObjects (issues with Threads and WebDriver ID's I don't know how to control) and the generation of the reports with Extent Report (were overwritten or overlapped after each test). The problem with doing it with containers is that each one generates a separate report, in addition to other problems such as access to the clipboard, or the download folders, or issues with permissions within folders/volumes created with the docker run command.

The final idea is to parallelize to complete a series of tests in less time, and in the end generate a single report of results. Any help would be appreciated. Thanks in advance.