Where to sell PS actions?

IMO it not something you will make money doing. Adobe exchange IMO is hard to put up with, Sell one copy the buyer can change it and distribute it as theirs.  I have I think only download one Action I did not change to work better for my work flow.  I download action mainly to read the steps to see how other use Photoshop.  Most Actions I have download were not worth the effort required to read and analyze.  Many were quite bad.  Occasionally I may get curious about a Action on the web and download it to read.  The best Action one has are the ones they create for themselves. Actions are not hard to record.

You'll recall that during the gold rush, it wasn't (invariably) the gold-diggers who made money but those who sold them the picks and shovels. Maybe you should investigate (in-depth) the various ways (e.g. publicity, marketing methods and distribution channels) of selling such products and sell that instead, or in addition to, your PS Actions.

As an example of this kind of thinking, here's a link to someone who sells advice to self-publishing authors:

https://selfpublishing.lpages.co/ads-waitlist/