When I do a structured workout, I like to pair it with badge hunting. I’d love to have a easy to filter routes based on whether I will be able to complete them given the time and power output in the workout.
Related, I’d also love to have a way to pick a W/kg I’m planning to ride at and see the estimated time it would take to finish a route.
For route time prediction in general Best Bike Split has Zwift section. Don’t know the 100% accuracy on this but best bike split allows you to put in your weight and power data to predict the time on a route.
zwifterbikes.web.app is another option for that. It will adjust the estimate based on different bike/wheel choices. It lets you input your height, weight, and predicted power to affect the estimate as well.