Calligraphy I actually do know quite a bit about! My mother studied it for years as a hobby while while I was growing up. There is a difference between “formal” calligraphy and Meghan’s handwriting, but to a layperson those are nitpicking differences. Bottom line, she has nice handwriting, and yes, I can see why she was able to sell her services to hand write invitations etc.
If you are interested, formal calligraphy involves choosing the font you want to use, in which every letter is formed the same way, and then carefully planning out the spacing of each letter before forming them. You can then add decorative elements to the finished text if you like. It’s generally time consuming and normally you need special pen nibs for it (they are wide, like a highlighter tip). You can see the all-important spacing on this example picture. Very good calligraphers can freehand it, but you need to be pretty skilled to do so.
Meghan, by contrast, writes in nice copperplate handwriting (which used to be how all school children were taught to write 100 years ago, but not so much now) and then adds flourishes to individual letters. You can see it’s not consistent in this example - it’s on a couple of “h”s and “d”s in this extract, but not all. Still looks nice, though. To an expert, it’s not calligraphy, but then that’s not exactly a legally defined term, so meh.