That proprietary format is owned by a company associated with folks who won two nobel prizes for AI related work this year and the employer at the time of the researchers who wrote the attention is all you need paper and also the owner of a search engine with access to like, all the data. Doesn't seem unreasonable lol

I'll accept any open format that can be lightly edited and converted into PDF.

Google doc + PDF is likely the most commonly used combination based on what I see in the SEO spam.

Some of them make you watch ads and then allow you to download something that looks like a doc, but you'll find out soon that you downloaded a ppt with an image that you can't edit.