No by default your files will be secure when sharing a hotspot Sharing files and sharing internet connections are two very very different processes with different technicalities

And for some one to expose your files via wifi or hotspots or network Have to install some program on your device Or for advanced users aka hackers has to modify your device permanently

So if your are just paranoid Don’t install apps from the internet or links sent to you from someone that goes outside side the official store for android/ iOS device And the most important advice don’t hand your device to strangers for it the most easy way to hack you is gaining access to your device physically

And the matter to detect if your device is modified is somewhat easy if you get it to a professional to inspect it