I don't remember Tuello asking Serena to run away with him, I just remember him offering to send her somewhere away from Gilead. Was it to Hawaii? Tuello appears to be married, he told June "my family lives here" when she showed up at that plaza when he was running. I don't think he'd have thrown away his career and his 'life' for Serena at that point. If he was willing to do that, he'd have said the baby was his. IF what we speculate is true.
IDK, the finale didn't require too much suspension of disbelief on my part. Some of it made sense if you thought about it in a certain way.
If I'd been a handmaid I'd have traveled anywhere at any time to be in on a bit of revenge against one of the men responsible for what I went through. And I'm sure the former handmaids, Marthas, & Jezebels have an extensive 'grapevine' with each other 'so getting the word out' to the former handmaids wouldn't have taken much.
I think June's communications 'link' with Nick & Cdr Lawrence was Mayday. Then she brought in Tuello once she was sure of Cdr L's interest in the exchange plan. Cdr L would have told Gilead that he had been contacted and wanted to negotiate Fred's release in exchange for the 22 handmaids. That plan would have had to have had Gilead's cooperation. They wanted Fred back desperately as they really didn't know what/how many beans he'd already spilled. They were anxious to stop him talking so they were probably willing to 'overlook' Cdr L's ability to be contacted by June as well as his and Nick's ulterior motivation for wanting Fred dead. And I think the plan was executed (sorry about the pun) in complete secrecy so that neither the US nor the population of Gilead were even aware of it. What remains to be seen is how Fred's 'disappearance' will be explained away to Serena and thus to the world at large.
June has been told that Hannah has moved 'far away' from the area in which June lived in Gilead and that she is under heavy observation and guard. I don't remember who it was, but someone told her that Hannah is 'impossible to get to'. IMHO, she's 'bait'. They know that June will not be able to resist trying to rescue her.
Next season should be pretty good. The aftermath of Fred's death, Serena's baby, AL vs Janine & Esther, the further actions of June. I'm excited.