I have a speech disability, Can I use Alexa or Google for speech control, for example? My language is Finnish.
If you own an android phone you could try to see how well Google Assistant on that phone understands your speech. The Google Home experience should be comparable. On IOS the Google app can be used to test speech recognition. As for Alexa, the Amazon Alexa phone app should likewise give you some idea on their performance.
Both services are supported by Homey.