Edit: This calculation is for 1941.
Path 1
Resource mobilization gives us a ratio of soldier's pay and munitions:

Goldsmith's The Power of Victory gives us a crude estimate of German munitions output in 1944 dollars; something like prewar exchange rates (~2.5 : 1, RM: USD) gives us an RM value.

~= 15bn RM munitions production.
Back to Resource Mobilization's appendix C, where we get German net national product:

...note that NNP estimated to be ~8% lower than GNP.
Combining the foregoing we get:
- Armaments + Soldier Pay = (1.8 / .8) * 15bn = ~34bn RM
- Total Military spending = 71bn RM
- Military spending on non-armaments production and military services = 71-34bn = 37bn or 52%.
- Armaments as % of Total Military = 15/71bn = 21%
- Armaments as % of GNP at factor cost = 15 / (126 / .92) = 11%
- Soldier pay as % Total Military = 19/71bn = 26%
One big chunk of military services purchased would come from Wehrmacht payments to the Reichsbahn at .2 RM per axle-kilometer. History of the German National Railways by Mierzejewski. Total DRB revenue was 9bn RM in 1941; Wehrmacht must have paid a big portion of that.
Food and uniforms were probably the biggest single items in the residual budget for 1941.