Awww I feel for you, kid. Here are my ideas:
- I second putting ride POVs on the TV and watching ride-throughs of your faves.
- Also recreate your favorite snacks! (Mickey ice cream bars, popcorn, etc.)
- Watch your favorite Disney movies, sing along to the songs
- Find a really long line to stand in in the heat if you're missing that part of it

- Let your kid wear their ears around the house.
- Make your own "night time spectacular" in the backyard with sparklers.
- If you have a pool, buy some really over-the-top fun floats or backyard toys from Target and create your own mini water park.
- Get on a Zoom meeting and change the background image to the castle.
- Disney-bound at home with costumes and outfits inspired by your favorite characters.
- If they have any Disney character stuffed animals, make your own parade route through the living room
- Make a count-down calendar to your rescheduled trip date and decorate it with Disney stuff