I was speaking to a friend who recommended I do so. But I was looking for some extra opinions.
My experiences with the 1st 3 generations of pokemon gave me the opinion that pokemon wasn't really a plot heavy game (though lore/trivia can be surprisingly deep). The games are generally formulaic (gotta catch 'em all, 8 badges, a rival who usually takes a starter super effective against yours, a criminal organisation to wreck, an elite 4 and a champion to beat) Only big surprise I can recall with nostalgia googles in full effect is gen 2's double region. From what I vaguely recall reading SuMo was surprisingly plot heavy apparently.
My original plan was to just play Ultra SuMo as a remaster. Some of what I've read said I won't lose out on much by just playing Ultra, besides neatly seeing subversions of what happens in SuMo/the rest of the series? (One that I'm not sure might have been is rival picking a starter weak to mine).