This might be a good time to throw in some points on what makes a strong stand and what makes a poor stand as it does depend on detail more often than type of wood. Wood type does matter and pine is one of the weaker woods but how it is put together matters even more.
The first big thing to look at is how the weight is supported and that often makes us look at the joints as the vertical pieces are almost always strong enough if braced to avoid bowing in or out. So let's look for what we can see from ads?
I took a snip of a critical point in the Ivar ad. When dealing with a tank we need to make sure all four corners are well supported and level by wood which runs all the way from the top to floor with solid wood. That leaves different tank length to work better than other sizes might. Looking at the top of the Ivar we see the board is supported , not on the sides and front but by a screw in the corner, so this leaves the item totally bad for a short tank which doesn't extend far enough left/right to put the weight on the vertical boards. Even a ten gallon short tank may mean the weight is supported only by that single screw! But something longer might work if the sides hold the load rather than the top!
So look carefully at what is supporting the weight, is it laying on a board top which is on top of the sides or is it only the fasteners holding the weight? Screws tend to be good for holding from pulling out but very brittle and tend to snap if the pressure is put on the screw side. BAD one? Depends on tank length!
Same issue with the Rast pictured.
But then we have the Tarva which may/may not work, even though it is a different piece, it has some of the same problems. If we have a long enough tank, the weight rests on the verticals and those are a stack of wood and not prone to bowing down, but if we have a short tank, set in the middle of a thin board, not supported by any other horizontal I can see, the weight is only held by the top board and the more weight we put farther in from the side, the more likely (almost certain) the board will bow down. A short ten gallon is likely to crush this one while a tank long enough to let the weight rest on the sides might be better even if much heavier!
Notice how wide each of the growth rings are in pine? This indicates a fast growing tree which leaves these wide rings being much weaker than a slow growing hardwood tree which has much closer spacing on the rings. Wide rings bow quicker and split easier!
These could be made to work but then I can find much better, safer options for far less money if I look at the thrift stores for good solid furniture that is built in the best way and most of it will be far better wood type.
The devil truly is in the details!