Is it possible to get the NetSuite account number in a formula for a field or search?

natively i don't see it as available. You could add a field maybe that has it and then use that field.

I'm open to any idea. This has to do with links in a formula field when the account is refreshed. We had an issue yesterday where someone was updating production and thought it was from a sandbox link.

use a relative url

https://jcurvesolutions1.zendesk.com/hc/en-us/articles/209987966-Finding-your-NetSuite-Account-Number#:~:text=Note%3A%20Your%20Netsuite%20account%20number,to%20as%20your%20Account%20ID.&text=Go%20to%20Setup%20%3E%20Company%20%3E%20Company,under%20the%20Account%20ID%20field.

Relative url is not possible because it needs to point to the company's external website. So if it's sandbox it need to be

<https://dev.xxxxx>

and if it's production it needs to be

<https://www.xxxx>

This is being done view field formula so it's not scripted.