The same page, sent down every path
Your guests are not all in the same place. Half of them live in one WhatsApp group, a couple of older relatives only ever open SMS, someone insists on email, and the neighbours you are inviting in person would appreciate a card more than a text. A single shareable invitation link reaches all of them, because the link does not care which channel carried it.
Send it in a message, paste it into an email, or print it as a QR for someone to scan; each route opens the very same page. That matters more than it sounds: you are maintaining one invitation, not four slightly-different versions that fall out of sync the moment a detail changes.