Taking time value and returning a value that will pass a moment().isValid() check

Solution 1:

Docs: set, startOf.

const input = '14:29';
const [hour, minute] = input.split(':');

const myMoment = moment()
  .set({ hour, minute })
  .startOf('minute');

console.log(
 { myMoment, isValid: myMoment.isValid() }
)
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>

Note: this will respect the browser timezone meaning different users will get different moments in time, depending on their system's currently set timezone.
To set a particular timezone you might want to use .tz(). Docs: moment timezone.