Most brand names are pretty similar, I've used a couple of different ones, and they worked fine. Last time I bought two packs of VSGO and am happy with them. Cleaning your own sensor is nothing to be afraid of, it's not the scary mystery the internet makes it out to be. Follow the directions.
As to your weird blemish, that doesn't look like it's on the surface to me, it almost looks like some kind of delamination. Hope I'm wrong.
Have an A1 and a A7RIV really like the size as well as the view finder. Have a bunch of lenses including a fe 55 1.8 from 2014 when I bought my first A7. Works fine with these cameras
Would either wet clean it yourself if you are comfortable cleaning your sensor or take it in to local camera shop that offers cleaning and have them do it. I like photo solution swabs cleaning kits