There are many crypto developers on Upwork that you can hire but the payment is not crypto but I think you can contact the developer to request that you want to pay crypto instead.
Is it really possible to contact the seller and tell that you want to pay with crypto? Upwork doesn't allow this....
As far I know the buyer will get ban for sure, and if the seller responds and takes payments outside of upwork then it will lead to his/her account ban also.
There is also this one xbtfreelancer.com
There are no quality freelancers in xbtfreelancer.com
I tried many times but always failed to get a quality freelancer.
Though I find xbtfreelancer very useful to use as an escrow if the deal was made outside and later moved at xbtfreelancer.