Are there alternatives in setting up PBR environments?

I am trying to make a game for Android devices and other portables that incorporates the use of PBR. I was following this video tutorial.

In Player Settings where the teacher told to change the colour space to “Linear” is where I start to have problems.

Unity gave a message which says verbatim: “On Android, linear colorspace requires OpenGL ES 3.0 or Vulkan, uncheck ‘Automatic Graphics API’ to remove OpenGL ES 2 API and 'Minimum API Level must be at least Android 4.3”. To which I did, but upon doing so when I tried to build and run on my Android devices it then gave an error message saying these devices are not compatible with the selected OpenGL version.

The devices I use to build my game on are Samsung Galaxy S3 phone and Samsung Galaxy Tab 2 which I believe use OpenGL ES 2 or less.

With that said are there other alternatives in setting up PBR environments in Unity with the current devices I have? Do I have to stick back with the traditional old school texturing method?

Linear Color space is recommended but not strictly needed for PBR.

If I used Gamma instead of Linear Space, it gets rid of the warning, but I know it produces less accurate results.

From using Gamma, are there any extra steps to achieve the accurate results Linear Space provides? What are they and how they can be done?