How much can an atom ionize before becoming too difficult?

Question

For example, +1 is easy. How far can you go?

Can you get an oxygen nucleus with 0 electrons. (+8 charge)

What about the other way- how many electrons can you add before it is too hard to add any.

If the sky is the limit theoretically, what is the limit practically/under existing technology.

Answer 1

Practically for any atom to become an ion (+ve or -ve), it is energetically favorable only till, it attains the nearest noble gas configuration. After that, removal or addition of an electron, will be too hard to be done and will require a very large amount of energy, so it will be practically not possible.

Answer 2

A Lotz and a Lotz.