I think that building a major on Romania G1 tips your hand to the allies too much. It will give the UK some breathing room to be more aggressive IMO. Of course maybe you want to build a minor in Romania to make UK feel all warm and fuzzy inside, then when they don’t build home def UK1 buy transports G2 lol.
Anyway you have enough starting German units to push into both of the Russian front line minor ICs (Ukrainian and Leningrad) where you will use those ICs to build more German units as needed. You can start your move on Russia G2 if you want (especially if they fail to pull back from the front).
In the north you might need to buy a transport or two in the Baltic to threaten the northern IC to force the Russians to abandon it (or hit them hard if they try to stack it). Transports in the Baltic will also help you feed units into Norway/Finland, or more likely retake Norway if the allies make a landing there. Keeping some German navy in the Baltic for as long as you can will stall the allies from making landings in Scandinavia.
In the south you will have enough starting German slow units to push towards Ukraine (including your AA guns), but make sure to bring any surviving German mobile units from Paris through N Italy to Yugo on G2 so they can catch up to your front line units by G3 on Russian territory. An Italian can opener works well once on Russian territory. A couple Italian mech w/bmr used to open up territory next to the Russian stack so you can bring in a couple German ftrs for air cover (so the Russians can’t hit and run your southern stack).