The key is consent and right to deletion. GDPR is ok with you storing data if the user consents, you list all the data, you list who you share it with, and you have a contract with anyone you share data with so you can comply with a deletion request.
The US government won’t honor deletion requests for any IPs it requests from GA, therefore you can’t comply with GDPR if you use GA.
If you don’t share data it’s much simpler. You collect just what you need to do the processing the user consented to. And you delete it when a user asks.
Edited to add: I should say the 2nd paragraph seems to be the regulator's position. It seems a bit extreme to me and I don’t fully endorse it. But my main point was to try to highlight why most essential and consented processing is unaffected by this ruling.