Questions

What can Levati do besides making files smaller?

Three helpers in the same menu bar: capture whole web pages, windows or areas as an image, set the brightness of external displays and set the volume of each app separately. Making files smaller is still the main job.

Which permissions does Levati need?

Only for what you use, and only the first time: Screen Recording for captures, Accessibility for whole web pages and the brightness keys, System Audio Recording for volume per app. Everything stays on your Mac.