The main role sugar plays in canned fruits is for flavor. It also helps keep them from darkening a bit and helps them stay a little firmer. However, it is not necessary for safety. The amount of sugar (or none at all) is always your choice. Any liquid can be used to cover the fruit in the jar, peach juice works fine. Plain water also works. You may have difficulties getting enough juice from the peaches to cover them completely in the jar. You could add water or another fruit juice to supplement the peach juice you have.

Follow the same instructions as if using sugar syrup to cover the peaches. Processing time for peaches is 25 minutes for pints and 30 for quarts. Here are more details on preserving peaches.

https://extension.oregonstate.edu/sites/default/files/documents/8836/sp50444preservingpeaches.pdf

https://catalog.extension.oregonstate.edu/pnw199