After diving in source code i've found the answer: no argvs are passed, env are passed as NSProcessInfo.processInfo.environment (see NLContext.m):
JSValue *process = [JSValue valueWithObject:@{
@"platform": @"darwin",
@"argv": @[],
@"env": NSProcessInfo.processInfo.environment,
@"execPath": NSBundle.mainBundle.executablePath,
@"_asyncFlags": @{},
@"moduleLoadList": @[]
} inContext:context];
To modify them one need to add setters and pass variables before NLContext.attachToContext invocation is done.
PS. -1 to karma to 2 'close' voters. Hope my question and answer help somebody