maybe my ears are just sensitive but hearing the valve ticking/rattling few seconds after sitting for 1+ week is totally normal IMO. It’s just physics, the oil won’t stay in the heads by itself forever.
I usually drive only on the weekends during nice weather so all my cars that I ever had had valve clatter/ticking few seconds after a cold start. You will never notice this if you drive your car regularly.
The GR86 has the quietest valve train from the cars I had, because you can pre-oil/crank the engine so easily. On other cars you would have to pull a fuse to kill fuel pump to achieve this.