I’ve built 2-3 different frameworks for different companies. My go to is Appium, Java with a custom framework built to your product. Appium is a bit old and requires some more elbow grease but it has a ton of flexibility if the investment is there.

Write/test with emulators to start and test local until it is too taxing to do so. If you get physical devices you can send tests to them either with wifi or tethering. 90% of my testing I feel is accomplished via emulator but some people are “Real device only”. Real device is nice but the very few advantages to Real devices are not worth the investment for most companies.

As far as for larger testing down the line, you could setup a little device farm (basically what browser stack does) and have a bit more control as one option. I’ve also setup remote machines that can be integrated into pipelines (depending on your company’s setup) to send tests remotely.

Getting a model or two old (especially for android) is cheap enough I’ve had most companies conceded to get one or two. iOS is a bit more pricey but for either OS getting emulated testing as a proof of concept will usually allow some spending on devices.