nd how exactly is Trump going to enforce this? Building the Great (fire)Wall of America? Order all ISPs to transit using a filter as China does? Sure he could order google to remove them from their store, but people can still get the app using other means.
There are ways to bypass this, but the damage is still done. Most people aren't going to bother taking the few extra steps to bypass the ban so the company's going to suffer. Even if users do bypass it, the company's still banned from accepting transactions in coordination with major companies.
The ban is not on Americans downloading the apps, the ban is on companies subject to US jurisdiction from offering the apps for download. This is an important difference because downloading these apps will not get you in any kind of trouble (with the US government, but you will probably be spied on by the Chinese Government).
It would be best if people and businesses worldwide were to stop doing business with Huawei. The technology they use is likely stolen, and their equipment is likely able to either spy on you, or can be "bricked" by the Chinese government, or both.