Pico for Nextcloud

Pico for Nextcloud is an app, allowing users to designate any folder in their Nexcloud folder as site folder and have it served by Pico.

Install

Place files_picocms in your app folder.
Copy the folder samplesite to the folder of some user (it will be shared with users)
Set the uid of this user in the app settings
If necessary, modify the copied file samplesite/themes/default/fontello.css: Change url('/apps/files_picocms/lib/samplesite/themes/default/font/fontello.eot?13793670'); etc. to match your webroot, e.g. to url('/nextcloud/apps/files_picocms/lib/samplesite/themes/default/font/fontello.eot?13793670');
Set up your web server to redirect '/sites/some_site' to '/apps/files_picocms?site=some_site', via the two mod_rewrite rules:

RewriteRule ^sites/([^/]*)/(.*) /apps/files_picocms?site=$1&path=$2 [QSA,L]
RewriteRule ^sites/([^/]*) /apps/files_picocms?site=$1 [QSA,L]

If your Nextcloud is running under e.g. /nextcloud, modify accordingly.