Let's consider the Red Wings' acquisition of Staal to establish how much it's going to cost just to take Eriksson.
If the Rangers have a similar season (in the range of 95 points, finishing 15th or so), the Rangers will have to give up the 49th overall pick as part of the Staal trade.
The Rangers and Red Wings are not cash-poor teams: we need to stop looking at this specific move in terms of "real dollars in or out". The goal here is explicitly cap relief: the Rangers paid a mid-second in order to shed one year of a $5.7M hit.
Vancouver would be moving Eriksson for the same reason: the cash-dollars are not the problem, it's the fact that Eriksson's cap hit makes extending quality RFA's next season while icing a competitive roster borderline impossible.
Eriksson has two years of a $6M hit that needs to be moved: this represents 2.1x the cap hit that needs to be moved compared to Marc Staal. The math is simple then: Vancouver needs to send Detroit 2.1x the value of the 49th overall pick in the 2021 draft in order to complete the dump.
I'll use this as a reference for my values:
https://bluebulletreport.com/2019/06/05/2018-19-draft-model-update-part-iii-blue-bullet-draft-pick-value-chart/
We can see here that the 49th pick in next year's draft should have a value of approximately 4.3. Given that Eriksson is 2.1x the cap hit (term), Vancouver needs to find a sum value of about 9.1 in order to shed Eriksson. This is effectively equivalent in value to the #30 pick.
Jet Woo was taken with the #37 pick and just completed his D+2 season. Given that he's had the 2 seasons of development time, let's assume he's worth 20% more than the value of the #37 pick (+10% for each development year, assuming pick value at #37 for a defenceman, not overall). This gives Woo a value of 5.9, leaving us with a value of 3.2 left to add to the deal, which has a rough equivalency to the #71 pick.
How Vancouver chooses to bridge that gap is dependent on how their season unfolds, but an early indication would suggest that the best course of action - should Vancouver make the 2021 playoffs - would be to send the 2021 Vancouver 2nd Round Pick (assume it's #50) with Woo and acquire a 2021 4th round pick in return.
Personally, I think it would serve the Canucks better to pay exclusively in picks, but if you want to make Woo one of the main pieces going back, a late 2nd or early 3rd is really all it should take to make that dump. At least according to the math.