Formal:
* Advance look: Emphasizes the early access nature of the preview.
* Sneak peek: Similar to "advance look," but with a more informal tone.
* Pre-release: Focuses on the timing of the preview, before the official release.
* Pre-screening: Used specifically for movies or film screenings.
* Pre-show: Indicates a short presentation before the main event.
Informal:
* Glimpse: A brief look or view.
* Taste: A small sample of something, often used for food or entertainment.
* Sampler: A collection of short excerpts or demonstrations.
* Teaser: A short, attention-grabbing clip or advertisement.
* Trial: A brief opportunity to try something before committing.
Technical:
* Prototype: A preliminary model or design.
* Draft: A preliminary version of a written work.
* Test run: A trial performance or experiment.
* Pilot: A single episode or test version of a TV show or movie.
The best synonym to use will depend on the specific context and the intended meaning.