I just got another Decathlon one after old one died after three or four years. The sensor bit is identical to Wahoo Tickr, the OEM model number printed on it matches the Tickr.
Interesting. I was just having a look into this.
I read somewhere that it disconnects too easily which can be a problem while mountainbiking. Do you also have that experience?
Decathlon have one for £30. Worth a go?
https://www.decathlon.co.uk/p/dual-ant-bluetooth-smart-heart-rate-monitor-belt/_/R-p-128085