Thanks for the feedback! Due to this thread we'll slowly work on adding support for changing and uploading new models.
We were considering adding support for the viva project waifus https://viva-project.org/cards/characters since they have an active community that creates many waifus but haven't figured out how to implement that (each card ends up as a waifu model). They seem to currently have 36 waifus and keep their community keeps adding waifus.
Please let us know any more suggestions you have! Especially for which file format of 3d models you want us to support first, since there seem to be so many file formats.