Searching for a non-geek user friendly, I found dejadup is based on duplicity; and somebody already asked to add restic support to it:
https://bugs.launchpad.net/deja-dup/+bug/1800996
I think it would be nice from the desktop (aka no sysadmin server) point of view a program with a nice GUI, and no need for a cronjob to make backups
I think this is something to do for the Déjà Dup team. They made a front-end; they didn’t made duplicity (as far as I know) and Déjà Dup is not based on duplicity but it is a front-end for duplicity. Déjà Dup and duplicity are two different projects. Just like Relica (WebUI for Restic) and Restatic (Desktop UI for restic in process) are two different projects that happens to use Restic as the backend. I used Déjà Dup for a while and liked duplicity but the thing with Déjà Dup is that is really limited in options. I had to remove old backups manually from the terminal because I didn’t like the idea of keeping a minimum of six months (Déjà Dup is not as “smart” as deduplication tools so it takes a lot of space).
It would be nice to have some more options for non-so-geeky users; also someone else mentioned support for Borg in Déjà Dup, which would be awesome for Déjà Dup to have more backends but my opinion about Déjà Dup is that their team should put a little more effort in the options. Maybe put some “advance options” button somewhere, where you can set what you really want. I understand they made it simple for non-geeky users but the software is good, well integrated in gnome and others DE, and it would be nice to have more backends and advanced options. Maybe make the default options as it is right now but add some “advanced options” somewhere for people who would like to keep just, let’s say, 2 snapshots and delete the rest, for example. Or maybe some more complicated policies.
Overall, I think that would be a really great addition to DĂ©jĂ Dup.
I didn’t know about Restatic, I will look at it.
I was posting it because “maybe” the json output need to give some more information to be used as a backend; but I suppose dejadup team will contact restic team in that case. I use restic in crontab for some servers, and manually in console for my desktop; but being able to configure it in userspace for the rest of my family would be a bonus 
Probably a late answer but in case somebody is stumbling about this via web search: DĂ©jĂ Dup got Restic support in 2021.