Thanks for the additional color. I guess I had interpreted the below rules as allowing me to transit in Finland (end go landside) on the basis of my outward return journey to my EU country of residence from Russia. In any event, the current rules seem to be in place until 15 June so hopefully they enact new rules thereafter somehow softening the requirements. Will otherwise drop Finnish Border Agency an email to confirm.

4. Restriction category 2
Restriction category 2 applies to all external border traffic other than that referred to in Section 3. This category includes entry from Russia, the United Kingdom, the United States and Turkey, for example.

4.1 Permitted traffic in restriction category 2: third countries, for example Russia and the United States
Return to Finland
Finnish nationals and their family members
nationals of EU and Schengen countries residing in Finland and their family members
third-country nationals residing in Finland with a residence permit
UK citizens and their family members residing in Finland who the Withdrawal Agreement applies to
Return to or through other EU and Schengen countries
nationals of other EU and Schengen countries and their family members