How to use cloudflare without freenom domain?

Is there any other method to use this hosting with Cloudflare?

Cloudflare doesn’t allow second-level domains like https://YOUR_SITE_NAME.000webhostapp.com/

Freenom company periodically suspend domains without any notification, e.g. when your domain becomes quite popular (and it’s on the first pages in Google) and then mb sells them to someone else (and usually some guys use those popular domains for spamming)

Mb is there some other free domains (alternative to Freenom)?

99c domain?
Best to own your domain instead of relying on freeium ones.