I mean, science can be tested that's what makes it science. You don't need to source any materials from Russia to make isolate phages and create a therapy.

You just collect the bacteria you're targeting - which will in general have bacteriophages that have evolved to infect that bacteria - and isolate them.

Then culture a pure sample of the bacteria, add samples of the phages to petri dishes and look for plaques where it's killed the bacteria.

That's a very basic explanation and you need to do more testing to make sure it's safe to be used as a human therapy vs in vitro but, the science as far as the theory goes isn't fake and can be verified.

You can do it in your basement if you want, to target specific strains of bacteria that cause you acne for example. I wouldn't recommend that unless you're interested in learning about the mechanisms behind it and investing in equipment to create a safe and sterile environment.

That said - yes you can trust science from anywhere because the whole point of science is it's empirically verifiable.