Yeah, I installed that the other day. Why did you think it wouldn't be available? I've no idea what their support terms are these days but if a device runs it, makes sense to push it.
I'm used to the regular security updates, but assumed that a 6a would be ignored/purposefully excluded to encourage owners to upgrade to a more recent mobile, where Google have committed to x years of security and y years of operating system updates.
Contrary to all expectations,
my 2 1/2 year old Pixel 6a has just told me that Android 15 is available for download.