Portable version of Obsidian : no installation needed
cf https://share.note.sx/3vhfcdlc, using a fresh installation of obsidian (https://obsidian.md/download)
Download one of the compressed file (either zip or 7z), uncompress. You will get the PAF exe file, you can execute it from anywhere, a usb key for example. Execute, open your favorite vault (or create it)