Difference between Dan 2 and Dan 7 is there are 5 hegemons in v2 and 4 hegemons in v7. Marilyn right says it is insight to current day. My contention is that
a) the 5th hegemon is america of today.
b) that the Book of Revelation is a prophecy against Christians (in Christendom)
You rightly state that there should be no conflation between Christianity and Christendom. I assume that is a refutation of the Revelation is prophecy against Christians. I answered that with monarchial epicopates, the Christian will always be under the influence by state politics. It concerns the symbol on the forehead and right hand.
Why are the 10 commandments the 10 horns.
The 4th beast of Daniel is special as it is the only one with horns (Dan 7:8). The Strong's Concordance is H7162 (qeren) which is found only in Daniel 3:5; 3:5; 3:7; 3:10; 3:15; 7:7; 7:7; 7:8; 7:8; 7:8; 7:8; 7:11; 7:20; 7:21; 7:24.
Meaning
1. instrument of music, Daniel 3:5, Daniel 3:7, Daniel 3:10, Daniel 3:15.
2. symbolic, in vision, Daniel 7:7, 8 (3 times in verse); Daniel 7:11, 20 (twice in verse); Daniel 7:21, 24.
https://www.blueletterbible.org/lexicon/h7162/kjv/wlc/0-1/
If the prophecies are to be understood solely by the bible, only the Law fits into the 10 horns as a symbol in a vision that would cause Daniel great concern. If the 10 kings have not been found in the historical text, it will never be found.
Christianity became the state religion in roman empire and the subsequent christendom. The belief was expressed as obedience to the 10 commandments with trinity, sunday worship and icons.