I live in Finland, and while it is not universal it is extremely common for IT-companies to have a working-language of English.
The country is small and hires both immigrants, and people who specifically relocate to start working at the English-only companies, as well as local candidates.
Learning Finnish will obviously make your life easier, in many many ways, but companies themselves do not seem to expect or require it.
It’s definitely common in Denmark, enough that it’s a perennial national debate. Maersk is a huge employer that officially made their corporate language English something like 20 years ago, which spawned discussions about whether you should need to speak a foreign language to get a job in your own country. In practice the answer is yes, for some sectors.
I worked for years in an English-language work environment in Denmark (I am not Danish), and learned maybe a handful of phrases of spoken Danish the entire time. I was expected to be able to read the occasional email in Danish, but 1) written Danish is not hard in comparison, and 2) even years ago Google Translate was good enough.
It would have been nice from a social perspective to have known more spoken Danish, but my employer didn’t really care, and it isn’t easy to learn if you don’t have strong local connections. Danes will just immediately switch to English by default, and even if you ask them to continue in Danish, you need a decent level of Danish pronunciation to make yourself understood, which is not trivial to get to.
In The Netherlands I think it's pretty rare to require Dutch in IT related jobs. I know of one software company that recently initiated a policy of only hiring Dutch speakers and I suspect it will really hurt their hiring going forward. When they initiated the policy they also retroactively exempted all the great developers that already worked there who could not speak Dutch.
I've heard this before about Finland and found it really interesting as to my knowledge English isn't particularly more societally prevalent in Finland than in nearby countries such as Sweden, Denmark or the Netherlands. Any idea if it's as common in those countries as well? By the sounds of it in Finland there's more IT companies operating in English than in Finnish.