Sorry to say there is no such thing as selling tax credits, at least as you are describing in using previous losses of RVX.

In the US, see IRS code section 382. A quick google of Canadain tax laws tells me there are similar restrictions in Canada. Basically there are tax laws in place that effectively remove the incentive to acquire a company simply for their tax losses. So all of this discussion that the value of RVX doesn't reflect the value of tax losses in totally off base IMO. It does because that value is almost nil.

I have seen Canadian mining companies sell "flow through" shares in which losses are allowed to go to the investors of the shares. I have wondered if Canadian bio techs could do the same?

https://www.miningtaxcanada.com/flow-through-shares/