I have purchased two dot pro domains but the holder info is exposed.
Is it possible to use Whois Guard or the like on dot pro domains? If so, Do you know any service provider or registrar that offers this?
The dot PRO domain names have tighter rules compared to the likes of .com, .org, .net. currently and most likely indefinite you can not use private whois information on any PRO domain names from any Registrars. This is set by Afilias and makes sense because entities are validated by government certification which is periodically checked against whois data. I also believe this information is covered in your terms and conditions as well as Who Eligible for DOT PRO Domains.
Quote from Afilias DOT Pro FAQ
Is WHOIS privacy supported?
In order to ensure that the owner of a domain is a qualified registrant, the .PRO registry does not support WHOIS privacy.