10 meters from you vs. in 10 meters from you

Solution 1:

"There is a lion in 10 meters from you" is incorrect.

"There is a lion 10 meters from you" means there is a lion, and its distance from you is 10 meters (or, you know, approximatively 10 meters insofar as the person talking to you didn't take out their measuring stick).

"There is a lion within 10 meters of you" means there is a lion, and its distance from you is equal to or less than 10 meters, i.e. its position is within the disk defined by you at its center and a 10 meter radius.

See definition 2a here for the latter usage.

"The truck had stopped in several meters from me" is also incorrect, but is slightly closer to being correct, in that there is movement involved, not just being. You can use "in" when you're talking about an activity, and how it didn't, or won't, take more than a certain amount of meters. This is by analogy to the use of "in" with respect to time:

"I finished my homework in just 30 minutes!"
"I'll be there in a second!"

As described in definition 1.7 here and in the section called "used for expressions of time" here. In cases where distance is a relevant measurement that you would use in the same way you'd use a time measure, to say "this action happens within this spatial frame", then you can use it the same way :

"It's the ship that made the Kessel Run in less than twelve parsecs"

(that's a joke, because I'm pretty sure that in that quote "parsec" is mistakenly being used as a unit of time even though it's a unit of distance, but all the effort expended to rationalize it to make it valid indicates that it isn't grammatically wrong at least. Better example: )

"This truck will need refuelling in 50 kilometers"

I note that one difference between that and the truck stopping 10 meters from you is that the "in XXX [unit]" usually (always?) involves an absolute measurement, not one that is relative to a certain position. You wouldn't say "I will be there in 10 minutes from now". I suppose because the "in" construction itself implies that the measurement is relative to one's position before the action occurs.[citation needed I know]

So to answer your question, for those two sentences you would say

"There is a lion 10 meters from you"

and

"The truck had stopped several meters from me"

unless you meant something more specialized than those sentences suggest.