If you want to migrate content from or to a Plone site it is always the best use of ressources, if you ask volunteers to copy and paste the content items from one environment to another ;-(
But seriously: The Plone community created a tool for such tasks with a funny name: ‘Transmogrifier’. You could find some information on this at https://docs.plone.org/external/collective.transmogrifier/docs/source/index.html#transmogrifier and a training session at https://training.plone.org/5/transmogrifier/.
But it is not that easy and fast to create pipelines and blueprints for a migration yourself. Thus I recommend to ask and pay a Plone professional service to do the migration. It would preserve your nerves and you get results very fast.
I tried to have a look onto the TDF dashboard at https://dashboard.documentfoundation.org using an Internet Explorer 11, but with no success. The website didn’t render. I got only a retry of rendering actions. According to the browser stats at least 5.26 % of the internet user are not able to view the site (https://www.stetic.com/de/market-share/browser/).
And in addition for those who prefer webservices with ‘mobile first’ implementation: it’s not for you ;-(
The site doesn’t render proper on smaller mobile devices. It’s not usable on such devices.
I read a time ago about the myth of an expensive LibreOffice extensions and templates website. I investigated about this and had a look at the real numbers (they are public available on the wiki page: https://wiki.documentfoundation.org/TDF/Ledgers). I found some expenses only in two fiscal period: 2017 and 2018. TDF spent in 2017 6399.44 Euro and in 2018 642.60 Euro. The money was predominantly spent for content migration and an improved server environment. It included also an individual training for the TDF infrastructure team.
The most work on the website was done by volunteer work within some support from the Plone open source community. All in all TDF spent 7042.04 Euro for running the site for about seven and a half years, thus about 938.39 Euro per year. Seemed a very expensive tool in comparison to the financial and personal ressources used for running other TDF tools 😉
I updated my local instance from the new Plone 5.2 with the latest changes, created a copy of the Barceloneta theme and made some edits on its styles. It worked as expected. I could view my changes directly. Great tool!
I expanded the buildout from the Volto Github repository with one of my former Plone addons: tdf.extensionuploadcenter and added a new default view for it inside my own Volto app. I use this new view to improve my knowledge on Volto.