Simple website in pure PHP

Good day.  I need to create a very simple website/script in a few lines of code in pure PHP.  No frameworks, engines, databases - none of that should be included. The main task is simplicity and maximum speed. According to Lighthouse, everything should be green.

There is a sample website built exactly as I need it in pure PHP. My theme will be completely different and there will be a few important additions. But you can make an analogy based on the sample website with my additions, and I will adapt it to my theme. My theme is seedling seeds... but that's not important.

Here is the sample website we are reproducing https://michelmoran.pl/

The entire website consists of a stylesheet file and a PHP index file, along with nested folders containing text files.
I will outline the structure of the nested folders
1) In the root, folders with codes LANG (for example EN, ES, DE, AR, JP, etc.)
2) In each LANG folder, there are nested folders HOME and folders with brand names. For example, as in the website we are reproducing, these will be MostBet, PinUp, 1WIN, etc.
3) In the HOME folder and the brand folders, there are text files named 1.txt, 2.txt, and so on... let's say about 10 variants.
These files contain texts for the main page (different versions of texts) and for the brands (different versions). In the brand texts, there should be some indication of the tabulation displayed here https://michelmoran.pl/en/1xbet.html
That is, for this page, there is 1 text file in which the markup is somehow divided into menu tabs.
4) It is VERY important to also reproduce
User rating: <span itemprop="reviewRating" itemscope itemtype="http://schema.org/Rating">
<link rel='alternate' hreflang='' href='' />
And to be able to set the corresponding title and description for each language in each text file.

Now I will explain how it should work.
Here we have this script with folders where I filled in the texts. I upload all this to the domain. Upon the first visit to the main page of the domain, there is an automatic assembly and caching of the website structure, so it does not change anymore. How to implement this... well, that's up to your discretion and knowledge. That is:
1) The website will have as many language versions as there are LANG folders created
2) For the main page, the primary language and text are selected according to one randomly chosen text file from the HOME folder.
3) Then, for each language for each brand, 1 random version of the text is selected.
4) All this is launched in some configuration for this host (domain). Because if I access our script from another domain (host), upon the first request, a different version of the website should be formed where the main page can be in a different language and for all brands, different text file variants of content description can be selected.
5) There may be a situation where we have, say, 5 folders with LANG (languages), but the brands differ in each folder.
This is why we need to implement such internal linking as on the sample website. That is, on the main page, you can only select brands that correspond to the main LANG.

EXAMPLE:
If the main page is formed in ES lang, then from the main page, we need to create links only to the brands that are in the ES folder.
When I go from the main page to some brand of the same language, there should be links on the brand page to other brands of this LANG and the ability to change the language of THIS brand to the languages that are made for this brand. And when changing the language, the internal linking by brands may change since not all brands that were previously may be available in the new language, and new ones may be added. This is implemented on the sample website; you can click around.

CONCLUSION
1) Essentially, we are reproducing the sample website
2) Adding the ability to create different text versions of pages and the functionality of site generation (caching or configuration launch) upon the first visit to the site
3) You can reproduce the design that exists, but if it's not too difficult, it would be better to make it a lighter, simpler one that suits me (white background and blue, gray, orange, light blue elements of light design)
4) Preserve mobile layout
5) Achieve maximum speed and green Lighthouse metrics

I will be placing the site on a VPS. I can install any version of PHP
There are no urgent deadlines. Studios and teams with extravagant budgets will not be interested in this project since this will be an attempt for me to explore a new market for myself, and I cannot afford to spend a lot of money.

Wishing everyone peaceful skies!