A /motion command

With the upcoming game drop seemingly focusing more on user-made experiences (Sulfur cube's most prevalent usage being for survival-friendly minigames, the new attributes, etc.) I believe this would be a perfect time to give players the ability to apply motion (in a simple and intuitive way) to players, and other mobs.
The /motion command would be an amazing tool for datapackers and minigame makers, and would allow for lots of new mechanics to be implemented (Examples off the top of my head: Grappling hooks, player launchers, finely controlled knockback mechanics, making all mobs rideable, and more.) As of now, the game is already capable of modifying the motion of nearly all entities, all except the player. With this command, I want to not only give creators the ability to modify player motion, but also to add new features to make modifying entity motion more simple and dynamic. I believe the command syntax should look something like this:

/motion [target selector] [x] [y] [z]

[target selector] being the usual @p, @a, @s, @e, @n
[x], [y], and [z] being numbers that apply the motion of course, with the added ability to use the ~ and ^ modifiers. Writing the numbers as just plain doubles will set the target's motion to those numbers, adding the ~ will add the given motion to the entity's current motion, and finally ^ will add the motion given in relation to the target's view angle