I am really sorry to hear about your Dog. I knew I had to put my previous cat to sleep due to kidney failure and not wanting to have him suffer right at the end.
I gave him squeezy cheese straight from the tube, ham and chicken. We sat on the sofa and watched 'Cats and Dogs' (He was a Persian and the evil Mastermind was Mr Tinkles - another Persian). I told him how much I loved him and how sorry I was.... lots of tears...
We played 'Hand under the duvet' a lot, played with balls and string all weekend.
When it was time, I'd actually bought him a special bed and the nurse and vet came out to us, I didn't want it to happen at the surgery (I appreciate that may not be possible in current circumstances).
I spoke to a local Pet Crematorium beforehand, made various choices so that when the time came, it was already agreed and I could just grieve without having to deal with the 'details'. They were really, really good and gave me an update as to what was happening and when.
This was 8 years ago and it was still one of the most painful things I've had in my life. However.... I am so, so glad I had a few final days with him and am so glad he enjoyed them.
You're making the decision out of love - giving him a few final days full of love and happiness is such a lovely thing to do. Wishing you lots of strength.