Do not use snap. For many reasons.
On Arch, you can use code as @otherbarry suggested. It’s an open source build and does not have access to MS extension marketplace by default. It uses OpenVSX. But you can configure it to use MS extension marketplace.
If you want Vscodium, that is in the AUR.
Finally, If you want the proprietary build by MS, use visual-studio-code-bin from AUR.