From the available block at the documentation page:

https://www.zabbix.com/documentation/current/manual/config/items/itemtypes/zabbix_agent

Per <type> field if possible values are not available for all Linux agents there should be note.

These keys are not working on CentOS7/RedHat7/Ubuntu18:

zabbix_get -s 127.0.0.1 -p 10050 -k 'vfs.dev.read[,"bytes"]'
zabbix_get -s 127.0.0.1 -p 10050 -k 'vfs.dev.read[,"bps"]'

Please mark this ZBX as a documentation task if it is not a bug.