Hello
@LovelyLittlePanda
Strikers barely mention the story events in the main game, bar mentioning the main villain about once or twice (which isn't a big deal imo), so it won't spoil the main game for you that much, or barely at all. Some very integral characters in the main game aren't even mentioned here at all. It's mostly a contained story on its own.
However, at the same time you might find it hard to relate to the characters, since the game assumes you already know them from the main game and proceeds to use the chemistry already established between them in the group chat, instead of re-building it from scratch. No character gets much development here from the main cast, because they already had their development arc in the main game.
Other than that you'll be safe. If this is the only option you have and want to play it I don't find a problem in playing it and returning to 5 later, but of course, it's always better to play 5 first to get all the references and understand all characters.
I don't know if they're planning on bringing 5 to PC or not, might be a long time till this happen. I heard some could emulate it on PC using a PS3 emulator ? (Since yeah, the original P5 also came to PS3).