Sorry, I don’t see you mention what you were hoping for the card to do, what capabilities you were hoping to get.
To be honest, if you want to not risk killing your port or your motherboard, I’d highly suggest doing charging only. You just can’t adequately protect very high speed data lines at a reasonable cost from arcing, ESD, static electricity. You’ll find a good amount of discussion in the Full Power Magnetic Charging Card thread, I think about here is a good place to read from, at least for the inability to protect high speed data lines Full Power Magnetic Charging Card - #289 by Jonathan_Haas. Also, last I looked, Volta does not even attempt to claim that they have any ESD protection, they are just no different than any other random magnetic USB adapter. Other than a higher price, and spending money on a smooth looking website.
There are a couple reports in that thread of magnetic USB adapters killing ports. Also, this separate thread someone made after theirs was killed Don't use magnetic USB-C cables
If you’re just looking for charging, then that would be safer, plus easier. I think you only need the positive, negative / ground, and the two CC lines connected. A card like this might be a nice place to get into learning PCB design if you’re interested. There are some open source Framework Expansion cards you could use as a starting point, just editing an existing board. Here is one: DongleHider+. There are lots of youtube tutorials on basic KiCad, and online trace width calculators to tell you how wide you need for the desired current.
~edit~
This looks like a better board to start from GitHub - jack-greenberg/2sb: Framework double USB-C expansion card
Online KiCad viewer: https://kicanvas.org/?github=https%3A%2F%2Fgithub.com%2Fjack-greenberg%2F2sb%2Fblob%2Fmain%2F2usbc.kicad_pcb (Ctrl+scroll to zoom)
Delete all parts except for the male USB-C plug and one USB-C female jack. Move the jack to where you need it. Connect power, CC1 and CC2.