Can I create a volunteer form for NPO with Salesforce integration?

Sure you can.
FormTitan is very "NPO oriented". In fact, many non profits have been using it to create volunteer forms, donation forms,  applications forms, registrations, etc. In a nutshell, any form for a 501(c)(3) or NPO. Furthermore the forms they are creating are not static, simple forms - but rather sophisticated, smart forms with conditional logic and even Bi directional Salesforce integration. Read about the Lone soldier center for example.

The FormTitan Salesforce integration allows non profit organizations to
Push data to Salesforce - users can not only store data from the form on our servers, but also have this data "pushed" to the relevant objects in their Salesforce account. The push integration allows users to create records in SF and also to update and delete data in SF if needed.
Get data from Salesforce -  Users can extract data from their Salesforce account, and have it populated in their form fields.

Another important aspect of NPO work is the budget and formTitan has a good solution in this regard as well, because the prices for non profits are not only affordable, but the value you get for your money is also the best.