So as we know, the Swedish tree is a bit lacking when it comes to “heavy” vehicles, as the Swedish forces never really focused on heavy armor for combat during WW2.
For an example, the Strv m/42, which was Sweden’s medium tank during the war, is 2.7, while tanks from the same year (Like the Tiger 1 and M36 Jackson) is 5.7.
To compensate, Gaijin added the “Kungstiger” and Pz.271-1 (1942), and has considered adding the Krv Emil to the Swedish tree in one of the “passed to the developers” blogs.
What could also possibly be added is the Churchill Mk.III of which Sweden tested during the same time as the Tiger (aswell as a StuG III) to a lower BR like 3.7. This will in this case also strengthen Sweden’s (already pretty powerful) 3.7 - 4.0 lineup.
In general, Lend-Lease/Captured/Tested vehicles are usually frowned upon since it wouldn’t be fun if every Tech Tree had every vehicle. However, I am going to play into the controversial territory either way. If heavy tanks aren’t really your thing, and you are still interested in well-known tanks from the period, then i may suggest two tanks that could possibly strengthen the Swedish 4.7 and 6.0 lineup.
First off, the Panther A.
(If you can pay close attention, i believe the track you can see on the right side of the screen is the Kungstiger.)
When Sweden was trying to get their hands on a King Tiger around 1946-1947, they found a Panther A located at a tank depot outside Versailles. Much like the Tiger, the Panther was transported back home to Sweden, and then underwent testing.
While not really a heavy tank, it could fill in some spaces in the Swedish tree that lacks armor, since the only tanks at that battle rating with some actually decent armor are, in fact, not Swedish.
On the other side, the second tank might not have the same amount of armor, but still a decent gun compared to the Pz.271-1’s BR-350B or the Strv m/42 DT’s Slpgr 43.
That being the Sherman Firefly.

Excellent mobility, good gun, still lacks the rooftop .50cal. The armor might not be that great, but it makes up for it in firepower.
Now, why am i bringing up medium tanks in a message about heavy vehicles? It’s the armor, and the gun. While they’re not heavy tanks, they got enough armor to take a few hits and stay alive, while some Swedish tanks may crumble right after being hit.
On the more “lighter” side of the spectrum, aircraft. What does Sweden not have? dedicated heavy strike aircraft. In fact, the first “strike aircraft” makes an appearance at 7.0, so you have to either use the A 21A-3 (4.3), Bf 109G-3/6 (4.3/4.7) or the B 18/T 18s.
While these aircraft are doing an excellent job within CAS, there are still some BRs that lack CAS-dedicated aircraft. One of these examples is 3.7. Sweden did “develop” such a vehicle for said task, but was never completed. The BJ 24.

In theory, it would have been very similar to the Bf 110s we have ingame, being driven by DB605s and being able to have bombs sizing from eight 50kgs to a single 1000kg bomb. For offensive weaponry, four 8mm ksp m/22s in the nose and two 20mm akan m/41s in the fuselage.
If ground battles isn’t really your thing and you want to be one-tapped by a Bf 109, then this next one might be interesting for you.
In 1944, a few B-17G Fortresses diverted to Sweden after a bombing mission over Germany. A deal would go on to be made inbetween the Swedish and U.S. governments to permit ~300ish American crewmen to be repatriated in exchange for a promise not to use these crewmen in combat service and to formally turn over to Sweden the B-17s that had landed intact.
(source: worldairphotography.com)
Some of these B-17s would go on to be purchased by Sweden after the end of the war and were converted into airliners, but that’s not the important part.
In theory, since these B-17Gs had now been formally turned over (and later purchased), they were still combat ready up until they were converted into airliners. Sweden was still a neutral country, so a heavy bomber would make no sense to have either way.

If they weren’t converted to airliners though, there is a high chance that they could have been adopted by the Swedish Air Force, and fill in roles that both the domestically produced B 17 and B 18 currently had (bombing and reconnaissance.)
Once again, this topic is still pretty controversial since, again, this game would not be fun if everyone had the same vehicles. But it’s still fun to think of what Sweden could get for “heavier” roles than what we already have.