i was wondering if KH 0.2 BBS and KH HD 2.8 are different games? or they are on the same game? cause they have the same release date of KH HD 2.8 (sorry for the question i am seriously lost up until now on the story of the game)
I believe the question has been mostly answered, but I'll leave this open for you in case you have more questions.
For your own sake, I must specify that there are probably three titles in general that would be of interest to you.
All three of the remixes. I realize you don't own a PS3, but I don't think it's unreasonable to expect a PS4 port. Continue voicing this concern, it can't hurt - it Square sees enough of a demand then they will comply. I believe Yasue, the co-director of the series, has said that they've looked into it.
1.5 and 2.5 have most of the games you haven't played, with abridged cinematic versions of the DS games. 2.8 has the other game with two new experiences. 1.5, 2.5, and 2.8 will adequately prepare you for Kingdom Hearts 3. There is also a smart phone game called Unchained X worth at least checking out, though it's expected the major plot points of it will be covered in 2.8.