The film Galaxy Quest is a well-received affectionate parody of Star Trek and its fandom. It’s about the cast of a fictional Trek-like show (called Galaxy Quest) who are mistaken for an actual starship crew by a group of aliens.

Drama and hilarity ensue.

Episodic or serial?

There’s just the one movie, which is wholly standalone.

Idealistic or cynical?

Idealistic. It’s a parody, but an affectionate one which celebrates Trek and its fans.

Worth watching?

Absolutely. It is often hailed as one of the best Star Trek films despite not technically being one.

Anything else that should be watched first?

Nothing specific, since this is not part of actual Trek canon. Your enjoyment will be enhanced by a basic familiarity with The Original Series, since that’s the main point of reference (with clear parallels to Kirk/Shatner, Spock, Uhura, and various technology and tropes as seen in that series). But even more helpful would be just a familiarity with Star Trek’s cultural impact.

What should be watched after this?

If you’re looking for more lighthearted love letters to Star Trek, there’s always The Orville.