Does food enrichment replace meals?

Hi everyone,
I have a 7-month-old pup and I’m confused about balancing daily meals, enrichment toys, and training treats.

I work from home, and other than the walk, I feel like she gets too bored throughout the day. She eats 2 meals per day (AM and PM). Because it’s summer where I am from, I can only take her out for a walk in the evenings, as it’s too hot otherwise. I want to use food enrichments, but I worry about overfeeding and weight gain.

Questions:
1. Does enrichment count as part of the daily food, or is it “extra”?
2. If you don’t give food enrichment all day, what do pups do instead?
3. When walks are limited, how do you keep dogs mentally satisfied?
4. Do you use boots for hot pavement? What budget options work for hot weather?