It's not ideal but the awesome plone and awesome volto lists @pbauer mentioned are a good low effort compromise many communities now use.
There is a new solution to having addons that are ready to go in plone and it's plone distributions. I think that is a great low effort way for people to contribute by releasing a distribution of tested addons that work well together, with starter content and putting that distribution onto the one of the awesome lists.
When I started with Plone, it was really nice that there was a list of 'latest updated plugins' on the front page of plone. org (?) I would check 'what they did so I knew if I ever "needed that".
After all, I dont think I am the only one that have made code or an add-on just to discover later that someone else had already done the same.
There is a big difference by 'auto installing plugins' and 'showing what exists'.
Has anyone mentioned https://pypi.org/ yet? On PyPi you can filter by framework, in this case the Plone version you want the add-on for. Additionally, you can sort by 'relevance' and 'date last updated.' Furthermore, you can search within the context of the framework you selected. Very handy.
this is exactly what https://pag.derico.tech does under the hood ...
But https://pag.derico.tech does not give the same result as searching PyPi directly. For example, when I search https://pag.derico.tech for themes for my Plone version, I do not get the same results as I do on PyPi. On PyPi, I get a list of themes that I do not find on pag.derico.tech.
why not create something similar officially?
Would be cool if we make this official (the original plan).
@MrTango Possible sprint topic?
The Plone Addon Gallery (PAG) is all OSS and aggregates data from PyPI and Github.
The aggregator, currently needs to be updated to modern PyPI API's, that's why you don't see up to date info's on the prototype.
Feel free to jump on board.
But yeah, next sprint maybe 
Also it would be awesome to also aggregate the Plone packages from npmjs.org