I was looking for a list, now I see that I have to click on each slot...
As KK says there is no easy way to determine variance without knowing that.
a) The RTP of the slot remains unchanged.
b) The reel maps are known and remain unchanged.
c) The paytable remains constant.
d) The bonus round pick/award weighting is known and advertised.
e) The reels stop positions are not weighted at any time
f) Free spins reel maps are known and remain unchanged
g) Free spins are independent and A,B,C,D,E,F and indeed G all apply.
Assuming a fair RNG that would represent a truly fair slot where you could make a definitive statement on variance and I can assure you
No software I am aware of have all of the above boxes ticked but I should add not necessarily for nefarious reasons. For 5 reel slots with free spin rounds and multipliers the Mathematics becomes very involved and natural variance without control is a turn off for Casinos and indeed some designers.
If any software provider believes they meet all the above criteria then please let myself and the forum know.
There are places that may offer the above but the free spins do not have multipliers and these slots are very, very low variance. You also pay a "tax" on any winnings. They may also have set lines and set stake which is a fair way of maintaining some control on variance. (having the ability to change stake and lines dramatically every spin greatly effects on variance)
The Casino will make money with such a slot with A to G and estimated 97% RTP but they could easily lose money in the short to medium term. Faced with that choice or a slot with checks and controls where the variance and RTP can be altered at any time and guess which they go for?
Even licensed slots in your local casino do not have the checks of A to G but at least in properly regulated jurisdictions you will know the RTP.
Given all that take any variance charts with a pinch of salt even though there are certainly games with different variance out there.