I regularly make “GCN Energy Bars”, although I swap the oil for butter. For races, I cut them up into bite size pieces, in an open bag in the back pocket - it’s easier than opening a gel. When I did triathlon (up to Olympic) I used to have one at the start of the bike from a top tube bag. I’ve tried others, but I keep coming back to these as the easiest to make and keep!
On long weekend rides/ sportives/ audax, I’ve gone to bringing plain turkey sandwiches for the first few hours. Carbs from the (granary/ wholegrain) bread, some protein and limited fat. It seems to be working well for me. I never had on bike issues, but did used to suffer sugar crashes post ride going all sweet, particularly if I also did the post ride cake tables!