Ubuntu - GPU - Vulkan - Check what Vulkan implementations are currently installed

ls -al /usr/share/vulkan/icd.d/

returns:

total 36K
-rw-r--r-- 1 root root 161 Jun  8 19:06 dzn_icd.x86_64.json
-rw-r--r-- 1 root root 167 Jun  8 19:06 intel_hasvk_icd.i686.json
-rw-r--r-- 1 root root 169 Jun  8 19:06 intel_hasvk_icd.x86_64.json
-rw-r--r-- 1 root root 161 Jun  8 19:06 intel_icd.i686.json
-rw-r--r-- 1 root root 163 Jun  8 19:06 intel_icd.x86_64.json
-rw-r--r-- 1 root root 159 Jun  8 19:06 lvp_icd.i686.json
-rw-r--r-- 1 root root 161 Jun  8 19:06 lvp_icd.x86_64.json
-rw-r--r-- 1 root root 162 Jun  8 19:06 radeon_icd.i686.json
-rw-r--r-- 1 root root 164 Jun  8 19:06 radeon_icd.x86_64.json

NOTE: The Vulkan driver can be set with something similar to this:

export VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/radeon_icd.x86_64.json:/usr/share/vulkan/icd.d/radeon_icd.i686.json