Ask Lemmygrad

I'm not sure about other more "basic" things like artillery shells, small arms ammunition, etc. but you can pretty much assume that without China (specifically Taiwan and their semiconductors), they wouldn't have any modern weapons that rely on computer guidance systems, weapons control systems, and other things of that nature.

I stumbled upon this neat video showing the internals of a Javelin missile's guidance system a while ago, and who could have guessed, basically every chip inside that thing is stamped with "Made in Taiwan", even the ones made by "Texas" Instruments.

I'd assume this is the reason the current administration has been investing so heavily in bringing TSMC to the states (and failing), because they know they can't keep up their occupation of Taiwan forever and it would be devastating for them to lose what's essentially their only supply of semiconductors.

Texas Instruments still has a couple of fabrication plants operating in Texas that might be able to step in to produce some things, a lot of the chips you see in the video I linked above seem fairly "simple" and dated so I don't think it's too out of the realm of possibility that they might have the ability to produce these, but for anything much more modern than that, they basically rely solely on TSMC for fabrication.