Most people have a great idea to start a business but they do not have money to start. So they search for an investor to help them to start their business.
In my opinion, if you want to build a shelter for the animals, you should try with what you already have and do not ask about the donations because what you want to do is related to the animal's lives.
I watch a video in Snack or Tiktok or other media that some people start their own shelter at their home and use one small room to start taking care of the animals. Then they upload a video about what they did and that got a lot of attention from the audience and many of them are interested in adopting the kitten or dog.
Time goes by, now what they did become bigger and that attracts a non-profit institution to help that creative person build a better shelter for the animals.
The lesson of this is that everything starts from small and needs an effort to consistently do what we want because we believe that can become true in the future. The donations will come right away after you show how big your passion is for the animals.