What do investors from Russia have to do if they want to travel to Greece?

According to the latest notification valid up to July 5, 2021, travelers to Greece must complete coronavirus vaccination at least 14 days before traveling and present a vaccination certificate issued by a public authority. They are also required to show a negative PCR test taken within the last 72 hours, or 48 hours before their arrival in Greece, if it's a rapid test. Alternatively, a certificate proving recovery from illness can also be used. A valid European digital certificate COVID-19 is also acceptable.

No, there is no way to enter Greece without a PCR test even if you have Sputnik vaccination. This is due to the worsening of conditions related with the crisis in Russia.