Steve K. answered 04/21/20
BA in English & Comparative Literature & 40 years of reading IRS data.
You might have a case if the sponsorship & logo placement had an ascertainable FMV, but you would have to declare that as income since they paid you this for your efforts, and then deduct it as an equal expense for the time you invested producing their website. So it is a wash !
You have been doing the correct thing by not deducting any of it because gifts of your personal time is never a charitable donation. When you give something of value, you make a charitable contribution, but if you donate your time, your just doing something you enjoy. The IRS doesn't tax you on what you would have made or allows you to deduct foregone wages. They tax you on what you actually do make in a bonafide exchange.