I just picked up a banglejs 2 and I love it. I was using a galaxy smart watch 5 but didn't work without gapps on my lineage phone. Its obviously not as good as the Samsung smart watch but I've been super happy with it. No creating accounts, getting tokens etc. Just pair it via Bluetooth and gadget bridge and you are good to go. Its a little pricey but for open source watch its awesome, I've heard good things about pinetime as well.