Dad will be gifting me some money in 2026. An attorney is drafting up a gift letter with full explation. Attorney will witness and sign the letter along with dad. Dad is 95 years old. The doctor has agreed sound body and mind. This will be done in attorney's office. Any possible future dispute from estranged sister? Dad has adjusted will for this early advance, so end result will be 50/50 split. Location NY state.
If that is not of concern to you (your dad will be able to afford a nursing home on his own, and you will not end up homeless if your dad's house needs to be sold or will acquire a lien to repay Medicaid after he passes away), then go ahead.
You might also talk with the attorney about having your dad pay you directly, at full market wages, for the caregiving you are doing for him, to make up for the large salary cut you've taken to do this. You can't get paid retroactively, but you can set up a contract to be in effect going forward.
This is all to make sure that you have protected your own financial future during these many years of providing nearly full-time live-in care for your father.