Please help me crack my wallet!

Hi folks,

- throwaway for obvious reasons -

I hope there's someone out there who can help me. My father recently passed away very unexpectedly, and there was no opportunity for us to discuss the inheritance. It turns out he had a wallet few ETH on it - now owned by me. For someone living a modest life like me, this significantly changes my next few years for the better and, with the current high value (currently ofc. to the moon!), this is a bit of a game-changer for me.

That's why I have to try to crack the wallet, and I've been spending the last few weeks daily, investing countless hours trying to find clues, work out details, and educate myself on the whole subject from pretty much 0. Currently, I have an idea, but I'm so deep into it that I'm not sure if I'm not completely lost already. Therefore, I need your help, please!

I only have the keystore file, but: no password, no hint at a password (my father knew a lot about digital security), don't know the password length, no pattern, nothing. After all my research, there are just too many possibilities, so these options (hashcat, pyethrecover, ethcrack, etc.) are ruled out. OPHcrack as an option - to find a password pattern - failed due to my personal incompetence - for now.

But I couldn't believe that my father actually had no way to restore his wallet. So I kept searching and found a handwritten table with binary codes and equivalent HEX codes in a box of passwords. They are translated into a key from 0-9, like this:

0 = 0001111111100101 = 1FE5

1 = 1110111010010001 = EE91

2 = 1000000100111110 = 813E

...

9 = ...

For me, there were two options for using the table:

1. A numeric code with 16 digits results in a 64-digit HEX code. If "0x" didn't have to be included in the string, this could have been an option.
2. Therefore, I pursue this option: The combination of 8/16 binary or HEX codes results in a 12 or 24-digit BIP39 Mnemonic Phrase. Each of my binary codes has a valid binary/HEX for creating BIP39 words; there is no invalid combination of the codes i have. It seems to me as it was made for just this reason.

For 12 words, I would need an 8-digit numeric code, so 100,000,000 attempts. I think I (perhaps naively) consider it possible with a little Python coding and a good PC. For 24 words, I'm probably screwed.

Now I have the following questions:

- Am I completely going in the wrong direction? Is this how someone would encrypt a wallet recovery phrase as a nerd?- Are there other purposes for the table above, other than my assumption? For example, when setting up infrastructure for mining?- Could the resulting code be for something other than the mnemonic phrase?- Is there any way to reduce the number of possibilities for decryption? HEX decrypting is not an option as it has more possibilities than 0-9 even though its not all 16.

I would be immensely grateful if someone could help me. I appreciate all thoughts on this. Thank you so much!

PS: I would like to tip most helpful comments if I'm actually able to get access to my wallet.