Is there any way I can see if there's any more funds inside my Trezor? I remember, I already transferred out all of my funds from this hardware wallet, but I just want to be sure.
Like there's a way without buying again a Trezor Model One?
I wouldn't do what rdluffy suggested unless it's absolutely necessary. Regardless if you think you still have funds there or not, you would decrease the security of your coins by importing your seed from a hardware wallet into a hot software wallet. You said you moved your funds. Where? Did you transfer them to a different hardware wallet? If so, you could restart that wallet and import your old Trezor seed into it to see if there is still some crypto there. At least that way your security shouldn't decrease. I am hoping it's not a bad choice of a hardware wallet.
When you are done, restart it to factory settings again and switch seeds.