Scenario 2: I tell the bank I'm going to sell my home for sure (is
this a thing?), buy my new home first, move, and then immediately sell
my current home.
This is tricky and not a common "thing". You may have every intention of selling the first house, but Stuff Happens, and the bank really doesn't want to be left holding mortgages on two homes for a customer who can realistically only afford one. Of course, if the bank thinks you're capable of meeting the terms of both mortgages, they will happily loan you the money for the 2nd house under another mortgage. However, they won't just shuffle the mortgage from one house to another as part of the sale process.
You may be able to qualify for a bridge loan to pay off the mortgage on your existing house but you typically need substantial equity in your current home for those. Unless you have substantial assets aside from your house, you probably aren't going to be able to make scenario 2 work.
You are probably stuck with scenario #1.
You didn't ask, but unless you live in a region that's in the middle of a real estate bubble, selling a home you've had for only two years to buy another home is going to cost you a bundle. As the seller you are probably going to be on the hook for commissions, sales tax, other transaction costs. Depending on your mortgage you may even owe mortgage prepayment fees. Unless you have money to burn, you should try to avoid quick moves like this unless something like a new job or a family crisis requires it. Most folks try to stick around long enough for the (hoped for) appreciation in the value of the house to cover these costs.