The short answer is Trump's order had actual legal grounds to stick as far as Huawei goes.
Regarding Huawei , Trump basically told the Commerce Department to take action, Huawei was already (or was in the process of being) blacklisted by the commerce department, the commerce department does have the legal right to do that given the nature of Huawei's products and sensitivity of communications equipment.
The commerce department doesn't currently (although I believe lawmakers are looking into it) have the authority to simply blanket ban an app like tiktok on a whim / order. They simply can't do that for any old reason the POTUS says.
As I noted in another comment, in the US it does matter HOW you do things, the courts are independent (compared to say China) regardless how "right" someone might be they need to follow the law.
My understanding was that the real teeth behind both EOs is that they prohibited American companies from doing business with Huawei and TikTok. So Huawei would not be able to sell through American retailers, and TikTok wouldn't be available in the Apple store or the Play store, and they couldn't get an American CDN.
Those are the only powers that would be necessary to effectively ban TikTok from the US. Without app store access and without CDNs, TikTok would be dead in the US. And from my understanding of the Huawei situation, doing these by prohibiting US companies from doing business with TikTok is within the power of the President.
