Reddit mentions of Dell 7.4mm to 4.5mm DC Power Dongle Cable P/N: D5G6M .

Honestly, check around to see if you can get a second-hand dell charger, either USB-c or barrel connector. I just went looking and found a Dell adapter that goes from the old big barrel connector to USB-C for about $25, or one that goes from the old big one to the newer small one for about $10. You might be able to pick up an old Dell power brick for pretty cheap. It can just be so disappointing when 3rd party ones don't charge as fast as you'd like, or randomly stop charging at all. Also, Dell used to warranty any Dell product that was attached to your PC, so you might get a free warranty for a Dell one. *YMMV

link to that USB-C adapter (65W max):

https://www.dell.com/en-us/work/shop/dell-adapter-74mm-barrel-to-usb-c/apd/470-acfh/pc-accessories
Link to that old to new barrel adapter:

https://www.amazon.com/Dell-7-4mm-4-5mm-Power-Dongle/dp/B01JRHCFWW

​

For extra length, you might consider a normal, cheap small gauge extension cord instead of an expensive USB extension. AC power from the wall doesn't attenuate fast like DC power on the other side of your brick. I used to have a dell DC barrel connector extension for the old big cables. (It came with an auto/air kit they threw in for free.) But that was only good for my one laptop and a normal extension cord is good for everything and easy to replace.

​

Good luck!