Thats funny. The cashier at a nearby Dollar Tree offered me some if I didn’t find it elsewhere. I found some on Amazon. Just have to wait.

Off the top of my head, bagels only call for 4 ingredients. What’s unique is boiling them before baking. Can also add a cup of honey to the boiling water for a “little” sweetening up.

I use (but VERY rarely, making bagels is a more involved process than other breads) a recipe for whole wheat bagels from the Peter Reinhart baking book - “Whole Grain Breads”.
As you say - just flour, salt, instant yeast and a sweet syrup - honey or barley malt is recommended. Water too of course, but that doesn’t count as a fifth ingredient.
Peter Reinhart encourages using a “biga” and “soaker” when baking. These aren’t “water roux”, but they will have a similarish effect of locking moisture (and flavour) into the finished items.

this water roux for baking is fascinating. I recall the idea of flour & water for thickening a gravy but wouldn’t have connected it for baking. Very fun!! I’ll try it when baking something without moist (brown) bananas.