Yes, in many publishing scenarios you can use your own ISBN on Amazon. Whether you should depends on how much control and professionalism you want in your publishing setup.
Yes, many authors use their own ISBNs on Amazon instead of relying on Amazon's free options.
This is usually the better route when you want a more professional identifier and a setup that works more cleanly across the broader publishing ecosystem.
If you care about publishing seriously beyond a one-off experiment, using your own official ISBN is often the stronger long-term choice.
Yes, you can often use your own ISBN on Amazon, and many serious authors prefer to.
If you need official UK ISBNs, buy UK ISBNs here.