Hello,
I can use SP Page Builder in that version at my end. And I have shared the doc link where we have stated that too.
There should not be any issue with the latest version of SP Page Builder before & after migration. Kindly, make sure other components are Joomla 4 compatible as well before going to do this. We can not say anything about third party extensions as you can understand too.

And obviously taking a full site backup is a must to do, so if anything goes wrong you can revert back to your working backed up version.
Best Regards