The PureOS ISO download page at:
Show only checksums (secure checksums only [sha256|blake2] which is good)
- 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)