On what resource, client, you can quickly test the site on various platforms?

Question

JavaScript

Greetings! Thank you so much for taking the time to answer my question! :)
By the will of the crisis (my personal, not global;) the need to independently create a quality web resource.
But at the final stage, quite by accident, the following problem was discovered.
How to fix landing page background display issue on ios?
before discovering the above problem, I tested my work on virtual machines and on resources like this:
mobiletest.me
where the creators after registration promise the following:
"Mobile emulation allows you to see your websites
like they are rendered in mobile devices."
well, that is, rendering as in a virtual machine, which is very convenient, you don’t need to install xcode for ios to write a bunch of garbage in the terminal to speed up the process ...
in general, I really like the graphical shell, most likely they have api, so it’s very a nice-looking resource...
a couple of clicks, once entered the link and many dozens of the most modern devices at hand for verification.
see: (you can log in with my account [email protected];123456)

but, taking my example (link above):
the result of checking the operation of my site (ipad mini) on mobiletest.me - everything is as it should

BUT BUT BUT
here's how renders ipad mini actually

ios doesn't accept background-attachment: fixed like this...
Here's a set-up! Thank God I guessed to double-check everything...
&
On what resource, client, you can quickly test the site on various platforms?
Thanks in advance for your valuable guidance and advice!
&
ps I would really pay for such a service - this is an excellent start-up in my opinion, unless of course there are no sensible solutions.
a server, and two weeks of time for code and a mustache)))
even if you would have to download ridiculous 200GB with all the RAM to run the application...