Will having funds in a company account affect my DTV application as a German citizen?

You don’t have a bank account with the funds. Your company does.

As with nearly all Thai E–Visas, any Thai Embassy/Consulate processing and deciding whether to issue a Thai E–Visa will look for proof of funds to be in an individual/personal account, not business account.

It is at the discretion of the Thai Embassy/Consulate whether they will entertain accepting business accounts or not, and from the experience and reports of many over the years for various Thai Visas and situations, = it's an individual/personal account

However, I will not say never as there might be specific, individual circumstances at a specific Thai Embassy/Consulate with a particular Thai consular official where it might work, but keep things simple and straightforward is always a good thing!

The funds need to be in an account in the name of the applicant. Business accounts are not acceptable

Yes, that's no good and if don't have a HKID, as far as I understand you need to apply from Germany and follow their local embassy rules, which appear to be a little bit different than HK (I looked it up before briefly)

That can certainly be a problem, you need to have your own 500K, and even money in a company owned 100 percent by you, is not your own money.