I wish I could give you an educated solid guess, but there's not any sort of public plan or solid criteria for me to provide. If I had to guess, I am going to say they likely will not be added later if not available now.
I wish I had a better answer to offer!
The Samsung J series and LG Stylo are not flagship devices. They are low end to mid range phones. My aunt switched from an iPhone to the Samsung j phone about a year ago. At first she hated it once she learned how to make calls and text on it she was good to go.
As for the stylo phones. To me they are note phones for teenagers
Or intelligent people that understand the valid of a dollar and get the equivalent use from something a third the price. Why spend 3x the money on bling?