moving from x.wordpress.com to x.com

You will not lose any of your data when adding a custom domain. More on custom domains:
https://en.support.wordpress.com/domains/

Due to the differences between the free hosted blogs offered at wordpress.com and the self-hosted and self-installed version of WordPress supported here, if you have any further questions, please ask WordPress.com Support instead.

You’re welcome! I’m glad you found it useful.