The PureOS ISO download page at:
https://pureos.net/download.html
Show only checksums (secure checksums only [sha256|blake2] which is good)
but lack:
- filename information (such as: "pureos-3.0-live-amd64.hybrid.iso") of the downloaded file.
- PGP signing of the ISO itself or/and signing of the checksums.
a good example of downloading page (regarding to security) is from Qubes: (See 'Verify' column)
https://www.qubes-os.org/downloads/