I’m a little confused..
I’ve use my phone as a WiFi Hotspot on occasion for many years without ever adding an App.
I’ve used ‘el cheapo’ Huawei, and better phones like Samsungs, simply accessed the Setting and created a Hot Spot.
I’ve done all sorts from allowing several others to access the tinterweb, to Zoom and Team video meetings with very little issue.
The keys are - check your provider doesn’t set some sharing limit, which again has never caused me any problems, and of course ensuring you have sufficient Data, mostly mine have been unlimited, but more recently even with a monthly 20Gb allowance it’s not caused me problems.
I guess a ‘proper’ Wi-Fi device would be more powerful and probably better at accessing a reliable connection, but so far so good
( fyi - I’ve done this in the UK and abroad inc the US and odd places like S.Korea, and so far I’ve incurred no additional charges).