Preventing the purchase and import of physical equipment into the US is a lot different than preventing the import of code/speech. I fully understand the former is allowed, but I highly doubt the president possesses the authority to do the latter.
This has been the case since the launch of the App Store. It’s not new. When uploading an app to Apple App Store, you have to do disclosures about cryptography exports.
While I still vehemently believe the crypto export laws are a stinking pile of 1st Amendment violation, we're talking about code import here, and I don't think there's legislative precedent (and certainly not executive) to enact something like this.
I showed it to you, Huawei. USA gives a LOT of power to the President, sanctions, bans etc etc.