After a rather underwhelming experience with the Oppo Enco X2 (see quote above), I decided to try another DD/planar hybrid driver TWS, the Huawei FreeBuds Pro 2. The latter look extremely similar to the Oppos, but they're actually better suited for large ears and I was able to get a reliable seal with L-sized tips. However, the sound quality is not quite at eye level with the Oppos imo and frankly speaking, the default Devialet EQ preset is a warm bassy mess. I'm able to achieve more decent and neutral sound via the 10-band user EQ provided by the app, but the result still doesn't sound convincing enough to make me hold on to them.
So, back they'll go, just like the Oppos. And I'm holding on to my trusty JVC HA-FW1000T, which admittedly need rigorous EQ to sound good, but once properly equalized, beat the Huaweis in terms of SQ in my humble opinion.