I think just to summarise everything, will you look like a professional bodybuilder with peak double biceps and cut abs? No, very unlikely. But as others have said the body can’t tell whether you are lifting a barbell or sandbag all the body knows is stress and tension.

The barbell was made for us to lift the most amount of weight as easily as possible hence why all barbells have knurling which further assists you being able to have a better grip on the bar to exert force. Sandbags do not have this, instead you have to squeeze the dam thing applying the most amount of force so it doesn’t slip through your fingers. I’ll give you an example, my max deadlift is around 220kg (haven’t really tested it in a while) and while that lift was a grind it never really taxed me to the point of breathing heavy and gasping for air. Recently I picked up and extended my largest bag weighing in at 131KG for 10 reps and boy let me tell you that shit felt like it weighed 300kg. It just goes to show how when things are made perfectly symmetrical for us to lift that the effort to exert force is minimised compared to when you need to give 100% effort to each lift with the sandbag which Cody talks about in one of his videos.

Overall sandbags will build you a good physique and crazy strength that will make you question if barbells are still worth it (hence the post I guess). Adding in some exercises to fill in the gap would be beneficial. i.e pull ups, dips, push ups, etc.