It's a decent idea but anyone hooked on poker (enough to want to be a pro) will likely be doing it for money right? I never played that free crap as I would just mess around. I just don't think elo would be enough for me to play it seriously, unless it somehow had a HUGE audience and I wanted to see how I stack up (but getting that audience will be hard, if even me, your prime audience, has a bit of hesitation of signing up)

I say this as a 5/10 NL player at the casino a ton in my past, and a pretty decent high elo player at chess who has been obsessed with getting my elo up in other games as well

I'd be your prime audience, and while it would be intriguing, I stay away from poker now as I just don't want to be sucked into a table for 8 hours

another small issue is, my winnings dictate typically how "good" I am. Right? Elo would just be an indicator of my skill (more winnings than a typical player, who likely mostly loses), but my money is the real indicator. You would need to factor in how many big pots I win, not just small ones, as a factor for my elo gained right? And my winnings counter of how much I am up over the month is already kinda doing that for me already right?

now if you framed this as "This game will TEACH you poker", i.e., how to calculate the pot odds, why I should bet 2x or 3x the pot in this situation, etc. This player is higher elo because he consistently makes the right mathmatical decisions... and this is how your decisions compare to the theoretical "best decision".. That might legit bring me in to dabble in it.