Data found within the last Smash Bros. Ultimate patch makes it look unlikely that Sora is getting his own amiibo.
Or, to be more accurate, data that hasn't been found in the latest Smash Bros Ultimate update makes it seem likely that Sora isn't getting an amiibo. Smash Bros dataminers have dived into the files after the game's final update and have found amiibo data for Pyra, Mythra, and Kazuya, but not Sora.
One such dataminer, cloudnine987, revealed that Sora's amiibo data hasn't been added to the game, saying, "Pyra, Mythra, and Kazuya amiibo bins are in 13.0.1 but NOT sora. Given that sora is the only FP2 amiibo not announced, he's either really far away from release or isn't getting an amiibo".
This was speculated to be the case when Sora's amiibo was absent from his official reveal showcase. Sakurai went as far as to show off Pyra, Mythra, and Kazuya but didn't mention Sora at all during the segment. He even confirmed a vague release window for the three remaining amiibo, which made it seem like Sora wasn't going to get one at all.
There's a small chance that Sora's amiibo is in development and is just far away from being released, but if that were the case then his amiibo data should still have been added to the game in its final update. Sora is either getting an amiibo much later than everyone else that won't be able to create amiibo fighters, or he's being missed out entirely.
Sakurai has been surprisingly open about how difficult it was to get Sora in Smash Bros. Ultimate, so it seems likely that Disney drew the line at letting Nintendo make figures of their character to sell. Considering how much of Sora's Disney legacy has been scrubbed from the character in his Smash appearance, it probably isn't too much of a surprise that the big mouse house doesn't want Nintendo making any more content with him.