Lost Bitcoin treasury hunt

Long story short: I lost my father 6 years ago, which was a sudden and devastating blow to our family. Since his passing, I've been doing my best to take care of my mother. Recently, while discussing my investments with her, I mentioned that I was investing in BTC. To my surprise, she said, "Oh, your father was investing in it too."

My father's old computer is still sitting at my mother's home, untouched. I'm wondering what kind of old wallets could have been installed for BTC on an old computer running Debian as its operating system.

I have also found my father's pendrive with many passwords. If I knew what kind of wallet to look for, perhaps I could find it.

Any advice would be appreciated