Need advice on how to work with T-shirt knit to make this gift. [Self Drafted] Sewing Machines Parts and Sales in Los Angeles

The link is to someone’s closed Etsy shop.
As near as I can tell, she was just using a serger to put these two t-shirts together (which I do not have)
I only have a traditional (cheap) sewing machine with a zigzag stitch.

It seems to me the seam would be really annoying to wear. What would be the best technique to put these together and make it comfortable? I was thinking of adding a strip of knit along the seam so it could be folded back and stitched flat.

This would cause the stitching to show- but is the effort worth it to flatten this seam? It would not look as nice to see the stitching where I flattened the seam (or do you think most people would mind?)

How irritating would this seam be to wear?

Thanks for your input.