it wont effect windows install not having an external or secondary drive attached
Having a second drive connected during the install process will result in the small boot partition ending up on this second drive.
6 months from now, when that HDD gets disconnected to go elsewhere, no boot for you.
We see this here literally every day.
The way to fully ensure that this does not happen is to take the 10 seconds to disconnect the data and power cables from that second drive....ALL other drives.
Yes, it does that. Yes, we all hate that it does that.
But it DOES do that. Even if you only and purposely select the drive you want the OS on. The SSD in this case.
And of course, that also prevents the dreaded misclick. "Oops, I deleted the partitions on my HDD. It had all the photos of my kids/critical business data/2TB of games I cannot download again/whatever...."