Newbie question from potential Mac owner: which password is used for Keychain and App Store purchases?

I’m a heavy iOS user thinking of switching from Windows to Mac for various reasons, but I have a couple questions about how passwords work with Keychain / AutoFill and the App Store on the Mac. So, as I understand it, I’ll have my local Mac user password (which I’ll just call “local password”), and then I will have my (already existing) Apple Account password (aka Apple ID password, which I’ll just call “Apple password”). To login to my computer, I’d use my local password, which I’d create when setting up the Mac, right? And at some point during or after setup, I’ll login to my Apple Account on the Mac as well to allow access to my iCloud, Keychain, etc Now from that point forward, **which password would I use to AutoFill from my Keychain?** Would I use my local password (much like using Face ID, Touch ID, or the device pin on an iPad, iPhone, or Windows PC), or would I have to type in my Apple password every time? **And would this be the same password used when making a purchase in the Mac App Store, etc?** [I realize that Touch ID is an option with an official Mac keyboard or MacBook, but I am looking at Minis and hope to use my own mechanical keyboard] I know these are probably dumb questions haha. I’m mainly just worried about the annoyance of having to type in my complex Apple Account password constantly (as I obviously don’t want to make it simpler), and it’s been a little hard to be sure about how all of this works since terminology seems to be inconsistent in the Apple docs. Thank you so much!