Sounds like a great dapp idea!

I personally prefer having some relation to Steem in the name, in order to gain recognition & boost the platform's reputation. I used Launchaco's Name Service to make sure that these names are available on all social media sites as well as good domain names available. Here's my suggestion:

• SteemSafe (domain = steemsafe.app & username = steemsafeapp / trysteemsafe / getsteemsafe)
• Starchive (steem + archive, domain = starchive.network / starchive.zone & username = starchivezone)
• SteellHere (steem + still here... 乁(ツ)ㄏ, domain = steellhere.space, username = steellhere)

Here's some quick & dirty logo mockups to get a better reference of what these names look like in production:

SteemSafe	Starchive	SteellHere

I think my personal favorite would be Starchive, since I'm thinking ahead to the overall design of the app & can picture how stars & space can play into the theme of it all. For instance, if you go the subscription route you could have different price tiers called: "North Star", "Big Dipper", "Milky Way". The "file-uploading" icon could be a cluster of stars being formed or a shooting star, if you have temporary files that get deleted after awhile you could have them be "burning out", you could show all the files uploaded by a specific person in a "constellation" view. Stuff like that.

I also think that the notion of this being sort of a "next-gen" file storage service goes along with the space theme. Currently, everyone knows about "the cloud", wait until you introduce them to "the stars"! lol

Like I said, I really like the idea behind this dapp. Let me know if you need any help on the team, I'd love to join along and I can offer anything from Graphic Design work, Logo Creation, and / or Frontend Development (I know html, css, js, vue, svelte). Good luck with the progress! :^)