About the VM have a look at this (in English) https://git.duniter.org/nodes/common/doc/blob/rfc5-duniter-protocol-rework/rfc/0005%20New%20Scalable%20Blockchain%20Protocol.md
This one might also interest you (in French) [WIP] Ethereum Oracle for Duniter blockchain
And to replace POW there is this (in French) Abandonner la preuve de travail grâce a la toile de confiance?
Note that the POW we are using is quite “green”, I run it on a raspberry at home and it works perfectly well (when alone, it forges 1 block every 1-2 days). I currently also have another node that uses 1% of an Athlon which forges blocks several times a day. So the power needed on conventional hardware is almost negligible, thanks to the WOT, which is quite unique to Duniter (I haven’t seen that in any other crypto). In fact, it is using much less power than any POS coin I have minted in the past.