Overthinking that my app's site will not rank until buy Domain

so form 3days
i was thinking that my app or site will not rank untill i get ridd of on.render.com subdomain then finnaly i bought the fugofresh.fit domain it for my fugofresh app that is free and live on playstore!
u can check the app here: https://play.google.com/store/apps/details?id=rajibul.fugofresh.tracker
try the site too: https://fugofresh.fit/