Is it okay to mix bread flour and all-purpose flour when making a pizza dough?
That is absolutely fine. 00 flour is super-overpriced here, so much so that it is hardly ever used. Semolina is often used on the pizza peel, but really not all that often in the dough itself.

There are more recipes for pizza dough than probably anything else on the internet. Some use all-purpose flour, some use bread flour, and some use no wheat at all. You can get away anything with some experimentation.

Serious Eats has some of the best instruction around on everything pizza.

You don't say where you are from, but know that "all-purpose" flour has a different meaning to some people in India, and will behave differently than the medium-gluten wheat flour that is "all-purpose" to most of us. That doesn't mean you can't use maida (what is sold in much of India as "all-purpose" flour), just that it will behave differently.

There is no safety issue at all to mixing flour types. Assuming that the flours are safe individually, they will be safe combined.