htaccess rewrite subdomain to WP page

Hi all. Firstly, my apologies. I know this question isn’t specific to WP but after hours of Googling I can’t find the answer anywhere so I’m hoping another WP user has had to do something similar.

I have created a page which is located, for example, at https://website.com/foopage/. I’m trying to find out what I need to do in my .htaccess file so that when a visitor goes to https://bar.website.com they see https://website.com/foopage/. I have a straight-forward redirect at the moment but I would like the address bar to continue to show https://bar.website.com while viewing the page

https://website.com/foopage/ is a standalone, single page and nothing else will use bar.website.com subdomain.

Thanks in advance.

Edit: I used example URLs for the sake of simplicity but if you’re interested, the real URL is https://qsday.rocketcheetah.com