If your current tires are the stock ones: those are the weak point, not the suspension. The switch to 45mm tires with deeper threads (especially if you run them tubeless) will transform how your bike handle off-road.
The suspension is more complex. On the plus side, there is additional 12mm of additional travel and the switch to an air suspension. On the minus side, modifying the geometry and a risk voiding the warranty. Personally, it's not the choice I would have done. On the suspension itself, I would rather have chosen something like the Paragon Gold with 65mm of travel and that is actually lighter — and still offer the benefit of the air suspension. You would then only 'loose' the 12mm, but I think it's a minor benefit with potentially big drawbacks — gravel bikes often don't have suspension.
But for the budget, if you want to increase versatility, the choice I would have done is a second set of wheels: if you are still riding on roads, you could keep the stock wheels with tires on the road side and you can equip the second pair of wheels with tires further on the "off-road" side. A side benefit of that would be that you'll increase the inside width of the rims, which is better for large tires (the stock rims on the 2020 DS have an inside width of 17mm, which is not ideal for 45mm tires, even if it works).