Unique visitors Website vs Intranet

I have notices that a standard website measurable doesn’t only recognize a visitor on the first party cookie. Any visitor coming with a similar setup and system configuration (OS, browser version, user agent etc) will be stich to the same visitor. Regardless to different first party cookie values. Correct?

For a website with lots of traffic and many visitors coming from same organizations (B2B) that will have massive impact on the total number of visits and unique visitors.
I am working with a healthcare website running Goggle Analytics in parallel. Number of total pageviews match with in ± 5%. BUT number of visits shows 2,5 times less and visitors 3 times less in Matomo !?
GA pageviews/visits = 1,9
Matomo pageviews/visits = 5,9

The solution to get Matomo counting truly on first party cookie would be to user Intranet sites. In my tests it seams to work better and I will get a new visitors every time i delete my cookie. And 2 workstations with similar set up will be separated.

So the questions are:
Is there any drawback changing the Measurable to “Intarnet site” instead of “Website”?
Is there any way to force the “Website” measurable to only use FPC?
How exactly are the website doing the stitching (Fingerprinting)? Which attributes are used i.e IP, OS, user agent, Screen resolution?

Any help is appreciated.