I personally like the pen and a tough case.

Amazon.com: SUPCASE Unicorn Beetle Pro Case for Samsung Galaxy Z Fold 4 5G (2022), Full-Body Dual Layer Rugged Case with Built-in Screen Protector & Kickstand & S Pen Slot (Black) : Cell Phones & Accessories

I had one of the slide up S-Pen holders on my Fold 3 & it was a hassle. I prefer the Supcase Unicorn Beetle Pro for the Fold 4. The S-Pen is accessible when the hinge protector opens & there are no magnets. The hinge protector has to open & cover the hinge whenever the Fold is opened to use the inner screen so the S-Pen is there when ready.