Hello,
I'm the author of that page. Just like you might not trust that site, you shouldn't trust any answers to your question - including this one!
But here are some tips you can verify yourself, for this and other similar sites:
For the map/cartography updates, you can easily see that all files are hosted in "download-cde.tomtom.com". And TomTom is the provider of those maps/cartography:
https://www.tomtom.com/customers/groupe-psa/
For system/firmware updates, it's a bit more complicated:
For older versions, all files are hosted in "majestic-web.mpsa.com", and you could verify in a WHOIS service, such as
https://whois.domaintools.com/mpsa.com that domain is related to PSA/Stellantis.
Since the end of 2022, they start using Amazon CloudFront CDN - Content Delivery Network and all files are now hosted in "ds4emloty3shq.cloudfront.net", but there isn't a easy way to verify the ownership...
You also should know that all those updates are digitally signed and the car will refuse to install them if those signatures don't match.