Waterfox has a native sidebar/vertical tab feature along with container tabs that might fill your tab group needs (I stopped using chrome before they added tab groups so I watched a 4m video on them and seems like you could get all the features and more out of the sidebar).
I think it’s just a flat 100 searches trial, not per month. Of course you could use another burner email if you wanted to game the system but I think it’s worth paying for.