Re point 1: Depends on the country, but you can just found your own party in at least some EU countries.
Re point 2: Usually small parties in Europe do have a say in government, if they form a coalition with one of the big parties without an absolute majority (>50%). Yes, the big party will push through more of their own ideas, but the smaller party will get to make their own laws too - the big partner needs them to vote on their own laws too, so they can’t just ignore the smaller partner.
In some cases the parties even have received a roughly equal number of votes, so they get an almost equal say.
Re point 2: Usually small parties in Europe do have a say in government, if they form a coalition with one of the big parties without an absolute majority (>50%). Yes, the big party will push through more of their own ideas, but the smaller party will get to make their own laws too - the big partner needs them to vote on their own laws too, so they can’t just ignore the smaller partner.
In some cases the parties even have received a roughly equal number of votes, so they get an almost equal say.