A concept to private keys and seed phrases I’ve come to understand from being here. It’s supposed to be a you and you alone thing, never a third party. Should you happen to upload any of such online, sure it’s no longer private and you would be well aware that, you wouldn’t be the only one checking. Your even advised not to save your keys online and having these keys uploaded would be a worst mistake. The work you would be shying away from doing or find too rigorous would be something a team of get what we can would do in hours. So, just get going with what you’ve got. You already have a list of them, approach them in sequence.

Am curious though, just how did you OP, get hold of over 5000 private keys? Bought them in some sales or something? Or perhaps it’s the much you’ve had to generate within the Bitcoin existence time frame. That seems a lot.