For the cost of parking at TTC (the MK parking lot) you can watch the fireworks from the ferry dock, with the music pumped in. If it’s not NYE or 4th of July when access is restricted, you can walk to Poly and watch from their beach, ride the monorail to GF and watch from outside Gasparilla Grill or from the boat dock, or ride the monorail a little further to CR and watch from the 4th floor observation deck.
For watching Epcot fireworks you can park at DHS and then take the Skyliner or Friendship boat to the Boardwalk or the bridge between BW and Epcot. You’ll only see the high fireworks there - the view is not as good as the view of MK fireworks from TTC ferry dock.