I have bought several packages of these and they work great - https://www.amazon.com/Sinjimoru-Universal-Smartphones-Compatible-Accessories/dp/B09MDY421H/ref=sr_1_2?crid=257UPG1MHM3I7&keywords=magsafe+sticker&sprefix=magsafe+sticke%2Caps%2C236&sr=8-2
There are also thinner ones that you can put inside your case but it has to be a very thin case for it to hold well.
try this Sinjimoru ring. I was going to use it on the bare naked phone, but I decided to get a Spigen thin fit green color and it sticks on well and hasn't come off so far. it does have magnets so it isn't just a metal ring so there might be some interference with the S-pen, so far with my case there isn't any interference at all or if there is its very minimal. it also comes with a sticky pad that isn't at all thick that helps with adhesion to glass, etched glass I think, and then on the sticker itself you put the ring on it. haven't tested yet since I decided to put it on the case but I think it should work. also if you have any mag safe accessory attached then there will be interference with the S-Pen. just remove the accessory if you need to use the pen. also it will detect the pen as unpaired/lost if you reboot with an accessory. just remove the accessory and it should detect the pen again.
hey there! I use magsafe on my z fold 3 and love it, especially with how well the concept works with phones that change shape
https://www.amazon.com/dp/B09MDY421H?psc=1
here's the one i use, very strong
my favorite accessories are the car dock, wall mount, arm mount, and phone stand (self made)
YTF-Carbon Real carbon fiber case For Samsung Galaxy Z Fold 4 case ultra thin Aramid fiber Anti-fall Galaxy Z Fold 4 cover https://a.aliexpress.com/_Eyy1URZ aramid
Sinjimoru Universal Magnet... https://www.amazon.com/dp/B09MDY421H?ref=ppx_pop_mob_ap_share magsafe sticker
3 in 1 Magnetic Wireless Charger, 15W Fast Mag-Safe Charging Station for iPhone 13/12, 13/12 Pro, 13/12 Pro Max, 13/12 Mini, iWatch SE/7/6/5/4/3/2, Airpods 3/2/Pro (20W PD Adapter Included) https://a.co/d/77mtsWa 3 in 1 stand
15W Magnetic Wireless Car Charger Mount for iPhone 12/12 Pro/ 12 Mini/ 12 Pro Max, Fast Charging Auto-Alignment Air Vent Car Holder Charger- Compatible with Magsafe Charger/Magsafe Case https://a.co/d/6aEAAXm magsafe car charger mount