I have an onsite coming up. Should I bother preparing for Linux/networking/troubleshooting questions or will the interviews be exactly the same as standard SWE? Also if all goes well with the interviews, am I only limited to the SRE org during team matching? If it's just a SWE position I don't understand why I'm slotted to just SRE.
SWE-SRE is a SWE interview + NALSD round which IMO makes it harder than vanilla SWE. Can transfer between both as project changes.
No and yes. Because your recruiter will strong arm you into it and make it seem like those are the only opportunities available and because you filled/will fill out an application that is org specific.
Recruiters have an incentive to drive candidates towards SRE?
Recruiters are assigned to different teams/orgs. If the recruiter is an SRE recruiter, that's what they will try and recruit you to.