My 4yo daughter showed me the faster way to search m&g locations yesterday actually...she kinda did it by accident but still impressed that kids are sooo much better at technology haha.
On the My Disney Experience app, click on the map then change the drop down heading to “Characters”(the default is “wait times”). THEN in the top right of the screen, click on “Show list”, and it will give you every character alphabetically that has a M&G and you can click them to see locations and find on the map faster.
This won’t include characters that appear at meals or special events though, just the standard park meet and greets