Yes, its safety profile and production are well-established.

But as far as covid is concerned, it is some random drug. Metformin is also a wonder drug, should we bet our lives on it for covid? No? You say there are more useful things?

I really don't understand why people think this drug can work. It was trialled. It neither passed with flying colors nor flamed out. That's... pretty much what most drug candidates do. It doesn't really "remain to be seen" here: there's plenty of evidence for "doesn't move the needle".