I also noticed this, I’ve been using SaA on and off for quite a few years now. I don’t use it all the time because I don’t like having the phone on my bed and didn’t know until yesterday it could sync with watches. So, last night was my first night using it again. I was able to sync my sleep from both Samsung Health and SaA to Google Fit.
Sadly, I deleted SaA before updating/backing up my graph (it was early and didn’t realize it until as soon as it started deleting it). So, I can’t share those with you. I did have it sync’d with Google Fit before hand but it doesn’t show the graph/chart within their app (unless I just don’t know how to activate it).
According to SaA I slept 8 hr 8 min; going to bed at 12:00 am (exactly) and waking up at 8:07 am.
According to SH I slept a total of 7 hr 11 min, going to bed at 12:54 am and waking at 8:05 am.
So, they are pretty close on the wake up but almost an hour off in the going to bed. Maybe it’s because I manually start tracking on SaA and it starts tracking/says I’m sleeping as soon as I start? SH is automatic (I also have a Samsung Gear Fit2).