So here are the booting times with fresh install of Catalina:
- Stock Apple SSD 256GB (after PRAM reset) -> Swicth on to Apple logo almost the same time as the booting sound, 5-10 seconds to fully boot to login menu.
- Samsung 970 EVO 1TB (after PRAM reset) -> Swicth on to Apple logo at least 20-30 seconds after the booting sound (the screen stays black), then another 5 seconds to fully boot to login menu.
I've already selected the startup disk as the 970 EVO but loading times are still the same, maybe a placebo effect of few seconds faster.
Maybe could be a problem with ssd the adapter? I'm using one bought on Aliexpress (now I'm waiting for the Sintech one) and I covered the connector with Kapton Tape.
Also I'm thinking about that because in System Info under the NVME Express device tree, instead of "Apple SSD Controller" I got "Generic SSD Controller"
Speed test disk are fine compared to other online (around 1300MB/s in write mode and 1500MB/s in read mode). No other issues related to hybernation and sleep.