Ketchup produces a similarly sticky, tacky texture when used as a baked-on coating. If you use a ketchup with no added sugar, the result will still be somewhat sweet, but not nearly as sweet as with a sugary sauce.
Applesauce can have a similar effect. Again, use one without any added sugar. The result is mildly sweet rather than overwhelmingly sugary. For more control over the end result, make your own applesauce using tart apples rather than sweet ones.
Some other fruit and vegetable purees will work similarly. While I haven't tried these as a baked-on coating, I have made a variety of fruit leathers, and most of them go through a sticky-tacky phase. I imagine a puree of any winter squash, carrots, parsnips, plum, mango, or banana would work well. Of course the mango and banana versions will be quite sweet even without any added sugar. Some of the kinds of fruit that aren't usually eaten fresh, but only used for jams and jellies because of how tart they are, might be a good option. I'm thinking here of quinces, crabapples, etc.
Legumes and potatoes will probably not work - potatoes will end up like mashed potatoes, legumes get chalky and gritty when they dry out rather than sticky. Melons have too much water content for a simple puree to work as a coating, but you could reduce a melon puree by gentle simmering until it's thick enough to spread. If you wanted to experiment with a variety of ingredients with a minimum of effort, you could try using baby food.