Unfortunately that doesn’t work fo those of us in the US (and possibly other places?) because we don’t have the “gr” key on our computers.
What I’ve found (for those without that key) is this location: https://welsh.typeit.org/ where you can type just the letter you want or a whole word or more, then copy it into whatever you are writing. A bit clunky, but it works! There are also “alt #” things to get the to bach from your keyboard, but those don’t always work.
Finally, from my smart phone (when I remember I have it) there is a free keyboard layout that you can get called “Literatim” which allows you to type in other languages. You can specify which language you want to use and switch back and forth from your normal (phone) keyboard via a little icon in the bottom corner of the keyboard. Mine is set for Welsh, and it even includes predictive text in that language!