Left Hand Mode

Niagara Launcher lets you also access all your apps by scrolling on the left screen edge:

Why are there no plans for a dedicated left-hand mode?

We're not fans of mirroring the complete layout because most people are just so used to everything being left-aligned or centered. In our opinion, a right-aligned list looks clumsy, and we haven't seen any app yet that right aligns their app list. Moreover, only mirroring the alphabet wouldn't work; it would overlap with the app icons and names while scrolling.

Why is there no option to disable the invisible alphabet on the left side?

In our opinion, this toggle wouldn't be impactful enough. The only reason to add that option is to prevent the accidental triggering of the alphabet. We think the OS should handle accidental touches (palm rejection) because touching the edges accidentally can cause unintended behavior on almost every app. Phone manufacturers already implement this, but it might not be good enough. However, there are workarounds to achieve better palm rejection; for example, Samsung offers an app for that.