Your second part and edit on car manufacturers is spot on: they were set a quota of "US made" cars and had to build factories in the US as a condition to continue chalenging US local makers.
I'd call that gatekeeping
I see those actions as setting up barriers but they do prevent people who can't meet that barrier out. My thinking of gatekeeping is more absolute, as in "there is no way for you to enter here" and thus "breaking the gate" would have legal and/or diplomatic consequences.
So for me there are two concepts, trade barriers and gatekeeping. Tariffs come under the heading of trade barriers as well in my view.
In that sense, your view on gatekeeping would be more like what happened to Huawei and how they were straight banned from the US market.
It sometimes happens, but few things are so black and white in politics and market regulations IMO. Killing the viability of an import route by pushing the tarrifs outside of the reasonable range is often enough and helps to avoid "smoking gun" headlines.
Nokia on phones vs the Bell companies, Toshiba on laptops, pretty much everyone on the PC vs IBM, the entire Steel industry, the railroad industry before them, Japanese cars eating Detroit's lunch, Zenith and RCA's TV market, GE's appliance market.
Where is the gatekeeper in the Amazon/Aliexpress scenario? I'm sorry but I don't see that one yet.
EDIT: You did say "infra" and the best example I know of are the foreign car companies that set up factories here to build cars in the US to get around import issues.