Beginner Level 2
as one ui 2 is being launched One ui should be available for older devices from 2016
where in huge mobiles where made that time as S7 or Samsung first A series even J series those mobile are still freaking just needed some Software by which they'll still rule the generation. amoled screen are in these devices hence Black mode will boast the device overall User experience / Interference 
1 Comment
Not applicable
not possible according to Samsung agreement policy....they will not provide more than 2 major updates in devices...and Google pixel devices get maximum 3 to 4 major updates...Google restrict it to all devices except their own