Is it possible to do per pixel scale wiping/stretching ?

I know this is years ago, but in case someone is looking for a solution: Pixel Repeat creates this effect! I made the plugin myself, it stretches the last pixel(s) of a matte. Hope this is helpful!

This looks like CC Scale Wipe, which is bundled with AE. You'll find it in Effect>Transition>CC Scale Wipe

You can create this effect using Effect > Keying > Keylight. Even if you are not doing chroma key, it has an option to work over the edges of your image. Set the Source Crops for x&y axis to Repeat and change the values for Left, Right, Top or Bottom to recreate the effect you are looking for. Check the attached image.

I think that there is a plug-in called Pixel Sorter on Aescripts.com that recreates the effect with more advanced options but it's a paid one. https://aescripts.com/ae-pixel-sorter/

That kind of effect was popular about 10 years ago. It's easily recreated with a duplicate layer, a mask, and a huge x scale factor.

If you want to sample just the edge pixels then you could try duplicating the layer, masking the subject you want to stretch, duplicate the masked layer, animate the position of the middle copy, pre-compose the middle copy, apply the Echo effect to the pre-comp using the composite in front option, then use the top copy as a track matte for the animated pre-comp. You can get something like this quite easily. It looks like what you want to do. The screenshot shows the modified properties of all layers, the pre-comp just has a quick left to right animation, and yes, if you do a good roto, that will work with a moving subject and give you some very interesting results.

If you are curious, that's Me with Jessica Morris, our leading lady in our short film "Destiny". Look for the feature sometime late this year, and yes, that is how quickly I took advantage of the opportunity to photobomb our star.