'But, no matter' Versus 'But, doesn't matter'

[Tom]

Hi

Are the given expressions correct and interchangeable?

1- I have nothing to eat…but, doesn’t matter!
2- I have nothing to eat…but, no matter!

Tom

[Mister_Micawber]

.
I have repaired your punctuation and supplied a necessary pronoun. They are now essentially synonymous:

1- I have nothing to eat, but it/that doesn’t matter!
2- I have nothing to eat, but no matter!
.

[Pamela]

Why did you place commas after but, Tom? I wonder.

[Tom]

[b]

@Mister Micawber

I have repaired your punctuation and supplied a necessary pronoun. They are now essentially synonymous:

1- I have nothing to eat, but it/that doesn’t matter!
2- I have nothing to eat, but no matter!
.

[/b]

I liked the collocation essentially synonymous!

I would like to ask another question:

When in ( it is) no matter, the it part can be optional, why not in i doesn’t matter[/i]?

Tom

[Mister_Micawber]

.

When in (it is) no matter, the it part can be optional, why not in i doesn’t matter[/i]?

I don’t see that it is optional; only it is as a unit is optional.

However, without delving too deeply, I presume that it is because matter is a noun in complement in the first form while in the second form, matter is the verb. No matter is acceptable as elision; not matter is not.
.