it's time for law-makers to step in and force OEM's to have both systems preinstalled, with a choice at boot, like the EU did for browsers. linux doesn't even need more than a few GB of space so with todays disks the space is negligible.
The argument then is why just these two? What about the BSDs or DOS? What distro of Linux?
Realistically, the reason OEMs pre-install Windows has nothing to do with the storage space or even with the logistics for developing a "choose your os" program. It's that they get extra revenue from bloatware contracts.
Boutique PC or even laptop manufacturers are more than happy to provide Linux. They do not make enough machines to be viable for bloatware contracts, so for them it is often instead more profitable to get extra buyers by catering to niche user bases like Linux users.
oh, those two would be the minimum, you are welcome to add more. but only operating systems targeted at non-technical desktop users. so haiku maybe, but not BSD
and as a tech person, i would not care which linux distribution they choose. let the OEM pick one and use that as their differentiation point, if that's of any worth. ubuntu, fedora, suse, pop! os, whatever. it doesn't really matter, as long as there is an alternative to windows.