What I came across re. Regulations flying from Cyprus via Athens to Germany (with Pets in Hold or Cabin)

Regulations as of End February 2021-subject to change of course, and they DO change quite often, so better check with the relevant Website, Organizations, Airlines or Ministries.
When flying to Germany via Athens it means you are in Transit in Athens Airport. I always used to fill out the PLF (Passenger Locator Form for entry into Greece), but as we are only in Transit in the Airport I made some Inquiries and this is what I found out:

• • *International to international transfer passengers will not go through a COVID-19 test, nor do they need to complete the PLF and will proceed directly to Security Control and on to their departing gate.
    Source: https://en.aegeanair.com/passenger-locator-form/
    Upon Arrival in Greece Point Nr 4

• *Regarding Negative PCR Test upon Arrival in Germany:
  Exemptions from obligation to register (less than 24 hrs in Germany)
  Source: https://www.bundesgesundheitsministerium.de/coronavirus-infos-reisende/info-sheet.html
• Source: https://www.einreiseanmeldung.de/#/

• I also send an email to the Airport Bundespolizei in Munich (I assume the same will go for ALL Airports) asking about the exemption for the negative PCR Test if we spend less than 24 hrs in Germany.
  Answer: that is correct. Currently Cyprus is just a normal risk area, which means you won´t need a negative covid-test. If you want, you can still do a test here at Munich Airport.
  I would recommend to call your airline as well, it might be that they require a negative covid test onboard.
  Best regards,
  Mit freundlichen Grüßen
  Im Auftrag
  (Name greyed out)
  Polizeikommissar
  _______________________________________
  Bundespolizeiinspektion Flughafen München IV
• For the Return to Cyprus we will still need to fill out the Cyprusflightpass with Flight Data.(which can only be done 1 or 2 days before the intended Arrival Date in Cyprus. You CAN however prepare most of the Form well before that date and save it as a DRAFT on their Website, then 1 day before you can open the Draft Submission and fill out the Flight Info Details (which before were greyed out)
  Apparently (but to be confirmed) the Test upon Arrival will be free of charge for those coming from a “green” Country. Color Codes will be assigned weekly.
  Green Category
  This category will include countries deemed low-risk by the health ministry according to their epidemiological data.
  From March 1-31, passengers coming from countries in the Green category will be entitled to a free PCR laboratory test covered by the government.
  From April 1, there will be no restrictions.Orange Category
  Passengers coming from countries in the orange category will be required to have a laboratory test within 72 hours before departure and to have a certificate proving a negative PCR test.Red Category
  Passengers flying from countries in the red category will be required to have a PCR test up to 72 hours prior to departure for Cyprus, and will need to undergo a second PCR test upon arrival.
  No self-isolation will be required for those with negative results.

  Grey Category
  This category will concern countries not included on ECDC lists and those with unreliable epidemiological data.
  Individuals coming from countries in the grey category will need to obtain a special permit to enter Cyprus.
  They would also be required to enter compulsory self-isolation in accordance with the ministry of health’s instructions.
  Cypriot citizens, persons lawfully residing in the Republic of Cyprus and European citizens will be exempt from having to obtain a permit if flying from a country in this category.

Bear in mind ALL this is CURRENT (end of Feb. 2021) and can change quickly.
Happy traveling- I WILL :)