It seems as though the PC version was about three updates behind the Meta Quest release.
Espire 1 Convergence Update. Image of a future spy holding a silenced pistol.

A new update for Espire 1: VR Operative is out today for the Steam and Rift platforms. This update is called the Convergence Update and includes all of the content from updates 1.7, 1.8, and 1.9 that were already released for the Meta Quest version of the game. Publisher Tripwire Presents and developer Digital Lode say that there are some additional PC features that are also included in this update.

As this update is really a 4-in-1 update there is a lot of new content and changes that are included. There are new challenges, weaponry, and quality of life improvements that were previously Quest exclusive. There are apparently some "select challenges" that will remain exclusive to the Quest for reasons that neither Digital Lode nor Tripwire are sharing.

Details on the update can be found below. Espire 1: VR Operative is available for $19.99 (USD).

The Espire 1: Convergence Update includes:
  • New challenges
    • Furcata: Hostage Rescue challenge
    • Mangua: Takedown challenge
    • Crassipes: Sneaking challenge
    • Cicurina: Hostage Rescue challenge
    • Horcotes: Elimination challenge
  • New environment
    • Coober Pedy - Set in the remote underground mining town in South Australia of the same name, Espire Agents are charged with infiltrating Ophis’ headquarters in this new scenario, featuring a hotel, church, and series of caves interconnected by the twisted series of tunnels below.
  • New weapons
    • Spectre Silenced SMG and Sawn-off Shotgun are now playable in the campaign.
    • If players complete all of the SMG weapon challenges and all of the Sawn-off shotgun weapon challenges, these two guns will be unlocked for the campaign.
  • Major UI changes
  • Main Menu redesign - The Main Menu has been given a fresh new look, and a new "Latest News" UI panel has been added highlighting new content to players.
  • Expenditure summary
  • Removal of the 'flashback sequences' in the campaign.
  • Support for newer VR Headsets & controllers through Steam VR. This includes full support for Meta Quest headsets.
  • Upgrade to Unreal Engine 4.25, providing a fix for the game not launching on some newer PCs as well as minor visual and performance enhancements
  • Additional quality improvements and bug fixes.