Only a stool sample?  They are probably going to want DNA samples and retina scans as well.

If I remember correctly, ID.me is a third-party service.  I think it is interesting the IRS is paying a third-party service for this.

It will also be interesting whenever ID.me gets hacked.  It seems like something that will have a big 'target' on its head to be hacked, and realistically, it is likely a matter of "when" it will be hacked, rather than "if".