You can make a
request on the bug/request page and wait to see if enough players vote for this feature.
I'm curious as to what the goal of the variant is.
From a teaching perspective, I agree that calling out the card you are going to play, could be useful.
But, you can already do that by calling it out in the chat (without getting a free token).
If you just want to make the game easier, it would be very easy to start the game with 10 tokens instead of 8, for example.
As a developer, this full variant would require quite a lot of code changes because it introduces more actions from the players (choosing color + number).
It would be much much easier to just add a new easy mode with 10 tokens instead.
As with all the things we can change, we have to ask ourselves how useful it is (and for how many people) and how much time it will take to implement (and maintain).