However, regarding wallets, I'm preferring open-source products.
Me too, the problem that a lot of people have is that they lack the skills and kmowledge to verify the open source codes of these wallet softwares themselves. However, this is the reason why i always recommend that people go for well reviewed open source softwares, i.e. Electrum, so that even if you don't have the knowledge to verify the code yourself, you know that a large part of the community constantly does it.