So compiled a list of addition that can be made in the future, I tried to contact you about it, but never got an answer so at this point might do it here, it's the more sensible decision.

Italy-

-Brigata Alpina "Julia"
-Semovente da 90/53, an AT-Self-propelled gun.
-Ansaldo 9T, an Italian heavy-medium tank produced in few numbers in the late 30s.
-MIAS/MORA, a interesting tankette.
-FIAT 3000 Tipo 2, i.e. a upgraded FIAT 3000, with everything upgraded(engine, armour etc). and came in two variants, a 37mm cannon insted of the dual MGs, and another with dual MGs.
-P41 and M16 Celere Sahariano, a heavy and medium-light tank respectively, prototypes yes, but like the MAUS they were starting to be produced, but the war ended sooner than their deployment.
-Gruppo Sahariano, a light recon infantry squad.
-CV 33, predecessor of the in game CV 35, both used in combat.
-FIAT 3000 Semovente, a FIAT 3000 Tipo 2 converted into self-propelled gun, with an artillery piece.
-FIAT-Terni Tripoli, Armoured Car
-Lancia IZM, Armoured Car
-Semovente da 149/40, AT-Self-propelled gun
-Semovente L3 da 47/32, AT-Self-propelled gun
-Autolinda Lancia Lince, Armoured Carrier/Scout, similar to the Universal Carrier and Dingo(Very similar)
-AB43 Cannone, a variant of the AB43 with a 47mm cannon
-Renault 35 were in service in Italy too.

Poland-

-TKD, TK variant as self-propelled gun
-Haller Brigade
-TP14, prototype of a medium-light tank which wasn't produced due to the invasion in 39'
-KSUS, medium prototype tank
-PZInż. 130, light amphibius tank, very similar to the T38 and T37a
-WZ. 28, Armoured Car, predecessor to the WZ.34, but instead of being wheeled, has tracks.
-PZInż. 140, Light tank, sometimes referred to as the 4TP
-WZ.31, Armoured Car
-Renualt FT17, were still used by Poland


Hope it helped, I tried to stick to the ones we know existed and most were used.
Hope some if not all will come in the future, best regards and I love your work.
Sad we started with the wrong foot.