From ancient times to the modern day, Aristotle has been interpreted as holding this view. For example, Lactantius, writing around the end of the third century wrote:
"Plato asserts His monarchy, saying that there is but one God, by whom
the world was prepared and completed with wonderful order. Aristotle,
his disciple, admits that there is one mind which presides over the
world." Lactantius
After investigating this question extensively, Thomas Aquinas wrote:
"Aristotle’s conclusion is that there is one ruler of the whole
universe, the first mover, and one first intelligible object, and one
first good, whom above he called God (1074:C 2544), who is blessed for
ever and ever." Aquinas
The words of Aristotle themselves also make it clear that his metaphysics involve a belief in the existence of a single God:
"However, we must discuss this question by beginning with what has
already been laid down and established. For the first principle and
primary being is both essentially and accidentally immovable, but it
causes the primary motion, which is eternal and unique. And since that
which is moved must be moved by something else, the first mover must
be essentially immovable, and eternal motion must be caused by an
eternal mover, and a single motion by a single thing." Aristotle
In fact, Aristotle's theory simply does not admit of the possibility of there being more than one God. This is the basis for which he argues that his theory can explain the dilemma of contraries, such as that held by Empedocles who believed that love and strife are eternal principles in conflict. Aristotle considered such a view absurd, and he believed he avoided this difficulty precisely because there is only one primary mover:
"And on all other views it follows necessarily that there must be
something which is contrary to Wisdom or supreme knowledge, but on
ours it does not. For there is no contrary to that which is
primary,since all contraries involve matter, and that which has matter
exists potentially; and the ignorance which is contrary to Wisdom
would tend towards the contrary of the object of Wisdom; but that
which is primary has no contrary." Aristotle, Met. 12.1075b
He goes on to argue that a coherent understanding of the universe requires a single governing principle. As you noted, Aristotle seems to hold absolute truth as a presupposition, and any coherent theory about reality can only be harmonized by a belief in one God:
"Further, in virtue of what the numbers, or soul and body, or in
general the form and the object, are one, no one attempts to explain;
nor is it possible to do so except on our theory, that it is the
moving cause that makes them one. As for those who maintain that
mathematical number is the primary reality, and so go on generating
one substance after another and finding different principles for each
one, they make the substance of the universe incoherent (for one
substance in no way affects another by its existence or non-existence)
and give us a great many governing principles. But the world must not
be governed badly: The rule of many is not good; let one be the
ruler." Aristotle, Met. 12.1075b-1076a
Vasilis Politis summarizes Aristotle's view on the matter as follows:
"It is [Aristotle's] view that, strictly, there can only be one
ultimate cause of rational change in general — only one God. This is
because what Aristotle is searching for is the ultimate explanation
and cause of rational change in nature as a whole. But evidently there
can only be one such whole. So there can only be one ultimate
explanation and cause of it. It is perhaps above all because there can
only be one God that God cannot be identical with the inseparable form
of the outermost heaven. It is true that, in virtue of its spatial
position, there can only be one outermost heaven. For only one thing
can be outermost in space, i.e. can bound and delimit everything that
is in space and indeed space itself." Vasilis Politis