If the PLUX Biosignals Youtube channel has too little videos which might be interesting for us, currently only two:
https://www.youtube.com/channel/UCcWcxxG5TrksCFyDodY4ymw
we can find more PLUX Biosignals on Youtube outside of the channel. But there is also the channel from the Simon Fraser University in Canada about Wearable Technology and Human Physiology:
https://www.youtube.com/channel/UClU9XVBC0mDwJBIVJTUbtwg/videos
Joined Sep 11, 2020 with 38,928 views with 395 subscribers. The channel has similar projects as Bitalino Biosignals PLUX, some about ECG.
As far as low-cost high quality ECG devices are concerned, we can also find EMG/ECG Snap Electrode Cables in the OpenBCI shop:
and all the components to build an ECG device can also be found there. The instruction to build an OpenBCI ECG can be found in the web.