Considering the following four facts:
- Many western countries helped the anti-communist government during the Russian civil war,
- League of Nation supports Finland,
- The war lasts really long comparing to the Poland war,
- Due to the braveness of Finns, just one or two divisions with advanced armament will be enough to lock Soviet forces in the quagmire for longer. This is a typical low risk high reward investment.
It is hard to believe that no country significantly (i.e. more than one division of forces or advanced armament or significant trade blockage) helped Finland.
UK did plan to send 100k troops, but their main purpose seems to control the iron mines and avoid direct conflict with soviet forces.
In the last phase of the war, the most significant foreign supports were blocked or delayed by German:
- Hungarian volunteers were delayed by Germany.
- France planned to send 35k troops to directly fight against soviet army. But they are also blocked by Sweden, under the pressure of Germany.
- Italy sent massive amount of armament, but detained by German.
First, it is very weird that Germany would help Russia by blocking the supports from reaching Finland, because Germany itself started to plan an invasion into Russia after seen the incapability of soviet forces.
Second, even if the land route through Sweden is blocked by Germany and Sweden, other countries can still find other routes and send air/naval volunteers to help Finland.