Alternative plot
Here is my alternative outline for the show.
The Book Of Boba Fett
Fett escapes Tatooine. He steals a shuttle and makes a course for a business associate that can provide him with work.
The Empire has fallen although a few Imperials operate across the galaxy.
The New Republic has a list of the most wanted Imperial admirals and military officers. The New Republic want to capture and sentence them for war crimes.
Fett arrives at a civilian starbase and makes contact with his associate. The associate has top secret intel on the location of the highest ranked Imperial admiral still in hiding. He is launching strikes against Republic planets and military bases. The associate says the New Republic will pay a high amount to anyone that can track down the admiral.
Fett believes the high fee is worth the potential risk taking the bounty. He makes contact with the New Republic.
Fett offers to track down the admiral and bring him to justice. The New Republic don't trust Fett. He was on the payroll of the Empire, an enemy of the Rebel Alliance, but the New Republic believe his intel is genuine. They agree a covert mission and will pay him on delivery of the admiral.
The New Republic place a tracer on Fett's ship and track his journey. Fett senses they will follow him and possibly renege on the deal once the admiral is in Fett's custody. Fett plans to tell the admiral he's being used as bait to lure the admiral out of his hidden base so the Republic can assassinate him. Fett is playing both sides.
Fett convinces the admiral he can be his personal bodyguard but for a high price. The admiral pays for Fett for his services. This is just a ruse. Fett lures the admiral out of hiding. During a gun battle with Republic troopers the admiral is killed. The New Republic pay Fett for his services.
The remaining Imperials put out a termination warrant on Fett. Wanted dead or alive for crimes against the former Empire. The Imperials hire bounty hunters to track down Fett.
The New Republic will protect Fett if he gives up bounty hunting and pledge allegiance to the Republic. Fett declines. The New Republic leader grants Fett twenty four hour amnesty from prosecution. He must leave New Republic juridisction. After twenty four hours he is reclassified an enemy of the New Republic.
Fett undertakes a job to steal a valuable commodity and deliver it the client. During the mission he encounters an alien woman. They team up. She gets involved in his adventures as he battles the Imperial remants and bounty hunters. They form an emotional attachment.
Final episode is set five years later.
Fett has a family life on a remote planet. The Empire never found him. The New Republic never found him. The bounty hunters never found him.
Fett is working on his small agri-farm. His wife (the alien woman) has gone to work in a neaby town. His only child is at school.
A man approaches the farm. He talks to Fett.
“Rumour has it you used be to be a bounty hunter. The best.”
Fett continues his work.
“Fett? Your name is Boba Fett?”
Fett replies.
“I'm a busy man. Haven't time to talk to strangers.”
The man operates a holo-unit. An alien is shown on the display.
“Name your price.”
“I'm retired.”
“Think about it.”
Fett looks at the alien on the display. He's a wanted criminal. High value target,
The man places the holo-unit close by.
“I'll bid you good day, sir.”
The man starts walking away. Fett takes hold of the holo-unit and looks at the image of the criminal. Fett calls out.
“My price would be very high.”
“Naturally. I wouldn't expect anything less from a man of your renown. Are you interested?”
Fett smiles. A smile of interest.
Fade to black. End credits roll.
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My outline keeps Fett a mercenary. He doesn't protect or defend Tatooine. He plays both sides - the Fallen Empire and the Republic. That might be a way to keep the character faithful to the original George Lucas version as seen in the original trilogy.
Due to the narrative structure of a tv show you would need to expand the character. I suppose he could be completely one dimensional but that approach makes it harder for an audience to relate to the character. Giving him someone to care about, albeit still retaining his hard mercenary edge, would humanize him enough to appeal to a Disney + audience.