So one thing that I see in a lot of AH media is that whenever in a POD for a war or major political change happens weaponry used stays the same as OTL.
That's down to the hack writing of most AH media. We at AH.com can do better and have done better.
On a side note, here's a page collecting all sorts of military technology PODs:
https://www.alternatehistory.com/wiki/doku.php?id=pods:military_technology
You're bound to find something interesting there, including past discussions that touch up on questions you're asking in this thread.
I'll give a hypothetical example, say the Whites win the Russian Civil War in the early 1920's instead of the Bolsheviks, when you reach 1941 does the Russian army of this ATL still develop and adopt things like T-34s, PPSh's, Il-2's, etc? They don't have to have the same name mind you, just the same weapon system or something incredibly similar.
I forget where, but we once had one of those discussion on the Central Powers winning WWI and what their military designs would be like after the war. One of the debates in the thread noted very wisely that it's all too tempting to just give them the same sort of aircraft OTL post-Kaiser Germany developed, and ignore pre-WWI and WWI trends. If Imperial Germany had survived and been successful, it would make sense that it would pursue those trends, and later trends would be built upon that foundation. For instance, that same member highlighted how the Imperial German monocoque fighter designs wouldn't look like the OTL Bf/Me 109, but would probably be closer to a Fokker D.XXI.
A similar discussion (maybe the same one, I haven't checked) can be seen
here. Technology after a Central Powers victory.
Also, have a look
here. The British developing their own equivalent of a Sturmovik ground attack and close support plane during WWII.
If Tsarist Russia or a Russian Republic survives and prospers, and they have no need for a particular style of tank, gun or plane even two or three decades after WWI, they probably won't be building any. The USSR was a bit undergunned and had some inadequate equipment when the nazis invaded, but the Soviets did the best they could with their ingenuity, and with the material and time constraints they had. If those exact OTL conditions and challenges were not in place, it speaks to reason that the military technology developed and used could be quite different. For one, if no one bothers Russia after WWI, they'd probably still be using interwar era tanks and tankettes for years, with incremental improvements, before the next big armoured vehicle fleet upgrade.
I always get this nagging feeling that changing the outcome of a war or making it play out much differently would butterfly away at least some of OTL's military equipment.
It very definitely would butterfly away OTL developments, and the likelihood obviously increases with an earlier POD.
You really should take a look at the likes of EdT's
Fight and Be Right. He had military technology developments that fit the context of his world. From tank evolution, to warship evolution, to the sorts of military aircraft designed and deployed. It's quite divergent in some crucial details (based on the objectives pursued, or how things originate). When the TL's Great War errupts in the first half of the 1930s, the various powers are not fighting with WWI or WWII tactics known from OTL. Instead, they employ military tactics on roughly an OTL interwar era level of understanding and innovation. It makes for a really different progression of their world's only real equivalent to our world wars. The Great War starts by a Japanese assault on Formosa (Taiwan), where air power is crucial - a big part of the attack is parachuting in airborne troops.
Max's old
Chaos Timeline had one military power develop fairly robust tanks that were steam-powered and deployed during a war in North America, maybe one or two decades before they'd be in OTL. (The POD is centuries back.) They were a good example of "ATL technology that's understandable and plausible, but appropriately alien".
On the military developments front, Thande's
Look to the West goes borderline steampunk, with several powers developing military towing tractors and self-propelled artillery guns already in the 19th century. With steam propulsion, of course. Nothing fancy or fast, but gives certain sides a technological edge before newer technology shows up.