What if i only play the 3rd of each chord in a 1-6-4-5 chord progression, it of course sounds like the progression just without the extra notes. I'd also like to add that im not referring to chord tones, just looking for answer regarding using a singular note in a certain sequence to indicate a progression without the extra notes.
An interesting question.
Unfortunately, your question supposes that everyone will interpret the note sequence as indicating a chord progression, and the same progression at that.
Without context, most people will just hear what they might call a melody or tune. Some people might just call it random notes, depending on the sequence.
A single line can be reharmonized / recontextualized to suit any purpose, irrespective of whether or not it's an actual "melody" or if you've just isolated specific pitches from a give chord progression.
1-6-4-5. In C, the 3rds will be E-C-A-B. In isolation, those notes won't sound like thirds of anything. In fact, Hearing the E first, out of context, might well make the listener think the piece is actually in E.
On the assumption the listener realises it's in C, then the Am chord that you want to go next, and you represent with C note, could belong to an F chord, a C chord, even D7 or Dm7. Hearing the A next, probably wouldn't invoke a feel of an F chord any more than an A chord (and after a Dm7 imagined wouldn't be unreasonable), and the final B may well push the listener to consider 'ah, we're going back into E again'.
So, no, out of musical context, it won't map out the specific harmony you'd like. So there isn't a specific term for this, as the concept itself isn't specific.
An answer to the question in your title would be arpeggiation or broken chords. This is how you can indicate a chord progression with only a single line. Compound melody is another term for a melody that indicates a harmony (two harmonized lines.)
But the exact detail in the rest of your post describes a harmonically ambiguous single line.
Some unarpeggiated lines can suggests specific harmonies.
I-V-I. But the line only hints at this harmony, it could be something else. Also, with only one line we can't really tell anything about inversions. It could be
In your line it's hard to tell the notes are the third of the chords, because no chord root is used anywhere.
There is no problem with your line being harmonically ambiguous. But, if you want to use only a single line and you want the harmony clear you do need the 'extra notes.' They could be added with a little arpeggiation or compound melody.