A capacitive stylus will work but won't function the same as an active pen -- no pressure sensitivity.  The screen you have won't support that function. Even if you can get Dell to sell you the screen (and on a system this new it would be the only source), bear in mind that replacing the display will cost you the warranty on the system -- so it's not a practical upgrade.  Unless you're within 30 days of shipment, you won't have return privilege -- the least expensive path forward is to sell the system and buy one with the active screen you want, or consider buying a separate, active tablet to connect to the PC.  
Hi, in January 2022, I purchased the Dell laptop Inspiron 5406 2-in-1, with the hopes of being able to use it in my remote university classes (I'm a professor). To go along with it, I also purchased a PN350M Dell active pen. Unfortunately, I have just found out that this pen does not function with the HD display (which is the one I bought) and that if I wanted to use it I would have to purchase the FHD system or upgrade the screen display. This puts me in a bit of a pickle as I will be teaching classes soon.  I would like to know if there is a pen type that works on the aforementioned display, or whether my only option is to actually purchase a whole new one. Thanks, Gus.
Dell Inspiron 5406 2-in-1 FHD