K-9 Mail is an app available for Android which supports PGP (if clunkily).

<https://k9mail.app/>

I'm not going to remotely pretend that this would make PGP attractive or viable for the greater public. I do want to address your valid point that the general-purpose computer seems to be a dying breed, but that there are still options for mobile devices.

I've used K-9 Mail, though rarely do these days (it went poorly-maintained for a while).

There seem to be some options for iOS as well, such as iPG Mail, though I've no experience at all with it.

<https://www.openpgp.org/software/ipgmail/>

Most of my friends and family don't have Android devices.

Perhaps you might care to share with us what types of devices they do have, seeing as my mental telepathy transgizmatron happens to be in the shop presently.

Note that I also listed an iOS option, and mentioned that there are others.

Again: PGP-enabled email apps are available on many platforms, though, again, this addresses only a small part of the larger challenge at encouraging adoption.

there is definitely software to help with pgp on ANY tablet, phone, or PC your friends and family have access to. The universal problem is no one cares to encrypt except a few computer nerds, spooks, and journalists.

It means you now have to worry about key management or else lose access to all your old mail, it possibly complicates logging in on new devices or via webmail, partially breaks server-side (spam) filtering, breaks server-side full-text search… so there are some definitive trade-offs there to be made.