Regional subdomains via htaccess, how to do it via GET?

Question

htaccess

Good day to all.
On the site I'm trying to organize SEO subdomains by city. So that a person, after choosing a city, is redirected to city.domain.ru. Googled that in .htaccess it is necessary to register such a construction

RewriteCond %{HTTP_HOST} !^www\.
RewriteCond %{REQUEST_URI} !index\.php
RewriteCond %{HTTP_HOST} ^(.+?)\.dst.negabarite.work\.ru$
RewriteRule .* /index.php?city=%1 [L]

The idea is to get the city $_GET['city'] then and substitute it in the meta and texts. But the url needs to be exactly like this.
Plus, as I understand it, if you then go to another page, then the choice of the city will be erased. Maybe then somehow write it down in the session. In general, I do not know how best to organize it.
The site runs on WP, plugins and WP Multisite is not suitable for a number of reasons.
Now, when switching to the city.domain.ru subdomain, it redirects back to domain.ru.
Thank you very much in advance.

Answer 1

We solved the issue a little differently by registering Alias ​​on the hosting.