In a previous thread, I had begun to suspect that these ‘bistro’ or ‘Edison’ style string lights from Hazard Fraught might be dimmable, even though they do not advertise this fact.
One single comment on their product page clued me in to this possibility.
The other day I received my Gledopto GL-SD-003P DIN rail AC dimmers in the mail, and provisioned one of them on my Z2M network. I screwed in one single LED bulb[0], and plugged the string into an outlet I temporarily wired into the dimmer. And I was able to turn it on, off, and change brightness, via Z2M interface.
For some reason, not all the entities appeared in HA yet, but I suspect this is because I am still on really old HA version and I think some things changed in the way of MQTT provisioning in the meantime. I am actually working on upgrading HA this week, so I will try and remember to report back about this part when done.
Disclaimer: As they do not advertise these as dimmable, I suppose this ‘feature’ could stop working at any time. Harbor Freight are known to change suppliers and components over time. Usually this involves a change in SKU, but not always. Therefore, just to note for posterity, I purchased mine during the recent ‘Spring Black Friday’ sale, SKU is currently 56869 (as can be seen in link above).
Speaking of which, at only $17.99 (on sale) I found these to be a great bargain! They are quite decently made, quite bright, and spaced every 2’ (many competitors are spaced 3’). For the money I do not think you will find anything better, expecially when they are on sale.
Anyway, I am quite pleased with all of this, so I wanted to bring this model of string lights specifically to attention as being dimmable, and make a better headline for search purposes, so there you are. 
[0] The reason this is important is because some dimmers have a minimum amperage requirement. I could not find anything about this in the specs of this dimmer, so I thought I would try with a single bulb to test this aspect.