I don’t personally like the bars (although some people have noticed a variation in bar texture, I may have had a particularly dry freebie), but it’d be tough to find something in shops with comparable nutrition and low sugar levels. You’d be looking for a bar with high calories, but low GI (and thus low sugar) and enriched with vitamins and minerals. An internet search for ‘meal replacement bars’ would give you a few options, just briefly compare the nutrition to huel bars.
A more huelly option would be to try one of the following recipes (the muffins look particularly good):