Keep in mind this is a very 'zoomed out' view of the power grid. In reality every country is going to have grid limits internally and different sources of demand in different places.
For example, in your Finland observation it may be cheaper/easier to supply the north of Finland from Sweden rather than send the power that could otherwise go to Estonia to the other side of the country, probably not a lot of north south distribution internally in Finland because of terrain (I know Norway really struggles with this, you can see huge price differences in the north of Norway vs south of Norway on EPEX Spot - https://www.epexspot.com/en/market-data), so I would assume Finland is the same.
The UK also has huge bottlenecks north/south in distributing power. There's 4GW of HVDC planned to transmit power from Scotland to England, for example. Probably much more is going to be needed: https://en.m.wikipedia.org/wiki/Eastern_HVDC
As it happens this has been in the news quite a bit, and we've been told that the Finnish trunk lines are built for this [1]. Finland isn't split up into multiple electricity price areas unlike its neighbors.
For example, in your Finland observation it may be cheaper/easier to supply the north of Finland from Sweden rather than send the power that could otherwise go to Estonia to the other side of the country, probably not a lot of north south distribution internally in Finland because of terrain (I know Norway really struggles with this, you can see huge price differences in the north of Norway vs south of Norway on EPEX Spot - https://www.epexspot.com/en/market-data), so I would assume Finland is the same.
The UK also has huge bottlenecks north/south in distributing power. There's 4GW of HVDC planned to transmit power from Scotland to England, for example. Probably much more is going to be needed: https://en.m.wikipedia.org/wiki/Eastern_HVDC