> at the start, there is a PGP-signed copy of the text offered
Which shows you don't understand the problem.
HTTPS on content only sides is primary about preventing people with tampering with the website in ways which potentially can hurt you from just opening them. The increased trust-ability of the content is important too, but only secondary.
A PGP signed copy helps me to verify the content after I already fully loaded it with a lot of additional overhead.
It doesn't prevent JS injected into your side from being executed, does it prevent a injected http redirect to a fingerprinting site or similar (which e.g. could use non JS fingerprinting or potential non JS based RCE attack vectors, which luckily I haven't heard of in browsers in recent years but are not impossible at all.).
As long a browsers don't check the signature before loading/parsing any content it isn't secure.
EDIT: In general in 2021 using HTTS "doesn't cost you anything" (in the sense of nearly anyone can afford it), neither does it prevent you from still doing what you currently do (standing by PGP(oversimplified)) and being against the by now pretty much not-undoable not-decentralized HTTS infrastructure. But realism is a important part of security.
Which shows you don't understand the problem.
HTTPS on content only sides is primary about preventing people with tampering with the website in ways which potentially can hurt you from just opening them. The increased trust-ability of the content is important too, but only secondary.
A PGP signed copy helps me to verify the content after I already fully loaded it with a lot of additional overhead.
It doesn't prevent JS injected into your side from being executed, does it prevent a injected http redirect to a fingerprinting site or similar (which e.g. could use non JS fingerprinting or potential non JS based RCE attack vectors, which luckily I haven't heard of in browsers in recent years but are not impossible at all.).
As long a browsers don't check the signature before loading/parsing any content it isn't secure.
EDIT: In general in 2021 using HTTS "doesn't cost you anything" (in the sense of nearly anyone can afford it), neither does it prevent you from still doing what you currently do (standing by PGP(oversimplified)) and being against the by now pretty much not-undoable not-decentralized HTTS infrastructure. But realism is a important part of security.