Are Thunderbolt-enabled computers without Thunderbolt ports vulnerable to Thunderspy?

Could these two attack scenarios exploit the recently publicized vulnerability?

  • Using a Thunderbolt adapter like an USB-to-Thunderbolt adapter on a computer without any Thunderbolt port
  • Temporarily replacing hardware (mainboard) with hardware that has Intel’s Thunderbolt port

And if one or both would work: what would be a reliable way to protect against this on such computers (Thunderbolt-enabled or Thunderbolt not disabled and hardware-replaceable)?