tried [nativescript-rtl/ui] and it's good for a bunch of simple boxes, but not doing fine designing real layouts .. using it involve doing some fixing and re-positioning while abandoning some hopes and dreams of making things look like how you imagine them.

work fine with my project ( yahmini ): https://i.imgur.com/z1hskXM.gif

I think add RTL support in NativeScript Core is important and It's easy
NativeScript team should had added it to version 2 or 3

to support RTL you need reverse columns (you don't need reverse) from LTR to RTL (like android flexboxLayout)

then you should add RTL Language (i.e Arabic) to your application languages by using plugin like nativescript-i18n

IMG_5575.mp4.zip
Attaching a RtoL NS app video in which the page appears from Right instead of left

It's strange that Nativescript doesn't support RTL yet!
ReactNative and Flutter support it well but Nativescript not yet!
please provide it in next version.