Internet and phones aren't the issue. Its the chips
Internet, phones, Android aren't the issue - except if the US is able to push China out of GSM/ITU.
The real issue is the semiconductors - the actual silicon.
The majority of raw silicon wafers as well as the finished chips are created in the US or its most aligned allies: Japan, Taiwan. The dominant manufacturers of semiconductor equipment are also largely US with some Japanese and EU suppliers.
If Fabs can't sell to China, regardless of who actually paid to manufacture the chips, because Applied Materials has been banned from any business related to China, this is pretty severe for 5-10 years until the Chinese can ramp up their capacity.
China has some fabs now, but far too few to handle even just their internal demand - and tech export restrictions have long kept their leading edge capabilities significantly behind the cutting edge.
On the flip side: Foxconn, Huawei et al are so ubiquitous in the electronics global supply chain that US retail tech companies - specifically Apple - are going to be severely affected, or at least extremely vulnerable to being pushed forward as a hostage.