As long as they create self-contained sentences, periods/full stops are always a safe option, so you shouldn't need to worry about using them in either of these instances.
Arguably the first comma example should be replaced. As it is, it's splicing two unconnected ideas. A semicolon may seem 'speedier' but I would (personally) avoid even that here since the two parts don't seem (to me, absent context) to be sufficiently tied together to validate that choice. In any case, if this is text for children, the punctuation should be simple, i.e., use a period. If the text is for adults, they shouldn't be assumed to be two-mississippi-ing after periods and, consequently, periods should not be seen as slowing them down. So... just use a period.
In the second example, if not a safe period, a colon is perfectly fine: the dialogue is directly related to the preceding text. A copy edit along the lines of:—
Lacing it with sarcasm, Maddie laughed, "Mark, looks like you’ve got a friend."
would justify the comma according to the style I've acquired, but that's a much bigger change for the sake of a comma.
It all comes down to taste though, so take my comments with a pinch of salt.
Not just "subjectively extremely correct", the reader understanding your intention is the literal definition of communication.
The problem as a writer, though, is that you don't know if the "as long as" is going to hold. Punctuation as a set of rules that must be followed is certainly unhelpful nonsense, but punctuation as a tool to help point those who might be misdirected without it is worth some consideration.