You can create pages that are available for anonymous users without being logged in. I don't know what you want to build, but this might be a solution.
I don't know your use case, but I don't recommend skipping password authentication.
You can create a custom log in page for these particular users, and try implementing this
It is possible to create a custom login handler with Java in Mendix. I think that could be used to solve your problem.
However, the documentation for this is poor and you would need to look at some existing modules (e.g. the IP range validation module), to find out how it is working. (Edwin posted a good link)
Anonymous users as proposed by Andreas might be the easiest option.
This article on CustomLoginHandler should help you further as well: https://bartgroot.nl/mendix/custom-checks-on-login/