I bought a similar watch last month from AliExpress. Advertised as measuring blood pressure. Blood pressure was a random number generator between 117 and 125 and between 78 and 84. The last straw was laying the watch on my bathroom sink and getting 122/80. The seller would take no responsibility for selling a fraud, saying "blood pressure cannot be compared with medical equipment, please understand that just a reference range".

These are toys. Only a fool trusts their health to a $35 watch that does something the FDA won't even allow Samsung to do on their high end watches. I bought this one because I liked the look and thought it would be an OK smartwatch, but it isn't even that.

One of these cheap ones came up months ago.  It just gave fake readings all the time, as verified by a reddit sub.

Careful, you get what you pay for.