Travel to Russia: From which countries is this possible?

It is an uncertain time for travelers, as countries impose travel bans and the situation changes from one day to the next. The same goes for travel to Russia, which has begun changing the rules for certain foreigners.
What are these rules, exactly? You can find more detailed rules below:
Destinations
From August 1, flights resume with the United Kingdom, Turkey, Tanzania, and Abkhazia (Georgia).
From August 15, flights resume with Switzerland.
Three Russian cities can receive foreign flights: Moscow, Saint Petersburg and Rostov-on-Don.
The Russian state organ Rospotrebnadzor listed more countries which it recommends resuming flights. This includes Germany, China, the Netherlands, Denmark, Finland, Hungary, Italy, Norway, Poland, Mongolia, Sri Lanka, and Vietnam. Note that this does not yet mean that Russia allows flights with these countries, but this may happen in the future.
Russian officials have stated that they follow the rule where only countries that accept Russian citizens will in return be allowed to resume flights to Russia.
Travel to Russia: Arrival rules
Categories of foreigners who can travel to Russia include students, diplomats and their families, and foreigners whose visa status belong to the category ”highly qualified specialists”.
Foreigners entering Russia need to have a negative test against COVID-19 carried out within 72 hours before arrival. Note that this must be PCR tests, and these documents must be in English or Russian. Foreigners may also pay for a test at a Russian airport upon arrival, and a negative result allows them to continue their journey without further hassle.
Face masks and gloves are mandatory on planes.