These both sound like they would be interesting methods of setting up a multiplayer game. The first one sounds a bit more turn based and is almost a slow race to the finish-line. The second could could almost have saved games that would have an overlay so you didn't have to play right at the same time.
But to be clear, multiplayer isn't something we'd be able to build into Mini Metro. Multiplayer a really complex feature requires a bunch of planning to build it into the core of the game, so we're just not set up to support multiplayer at all. It's neat to think about what a new/different version of the game could have looked like though!