I would think any engine is rebuildable. I'm sure that someone even makes cylinder sleeves for it.

 

Prior to 2018, the engines used steel sleeves, so you can in theory replace them if they had severe wear. Starting in 2018, Ford used the plasma spray bore that deposited a thin coat of hardened steel onto the aluminum cylinder wall. This slightly increased the displacement (because there is no longer a steel liner). If you wore that out, you could in theory still replace it with a sleeve, bringing the displacement down slightly (back to that of the pre-2018 models).

 

Short answer maybe, but not really worth the effort. Replacement blocks are very cheap. From my experience the 5.0 is a good 200k+ engine and all mine have lasted to that point. So rebuild and replacement is way far out for most.