So, if you can sing than you can probably do this easily And I hate you. If not...
Ridiculously, this game currently allows you to place your mic against your TV / soundbar and bank a good amount of score (not perfects, I feel around 66%).
I've hit 80% a couple of times with this method, after trying properly a number of times and hitting ~75kish.
Finally nailed it with ease at "Clean Bandit with Jess Glynne - Real Love"
Good luck!