I jump off yellow river sand, BUT it doesn't get properly cold here (never snows, frost is rare) so I can't speak to its suitability in icy conditions. Be aware that literally anything will freeze if it's wet. Jumping outdoors is, as a blanket rule, unsafe in winter in places where the ground freezes.
The sand gets waterlogged if there's been days and days of heavy rain.
My favourite jumping surface is well-kept grass, but it's a lot of maintenance: watering, mowing, weeding, moving the jumps often so that the dirt doesn't get excessively compacted in any one area, aerating yearly (or more if the arena is in heavy use) for the same reason... it's like having a big lawn, but worse. Few places keep grass arenas in use for anything but competitions for this reason. But grass is nice and springy, and while it CAN be slippery in the wet, it's nowhere near as bad as mud.
Fancy arena footing has an unfortunate tendency to blow away if used outdoors, but whatever is in the indoor arena at Yalambi (the biggest showjumping farm near me) is absolutely lovely too. Nice and cushiony, not bad to fall on, tastes slightly better than dirt. Ask me how I know 😂 😅 & the horses jump really well off it too, but I guarantee you it cost an arm and a leg, and probably a few kidneys too. Their horses jump the 1.50s and up, mine aren't quite to that standard (yet?) :P
Good footing for jumping cushions impacts but isn't excessively deep, doesn't go excessively slippery or heavy when it rains, is easy to walk on, doesn't get all compacted when used, and acts as a good, stable surface for the jumps to sit on. That's a lot of demands for a material suitable for outdoor use, that won't blow away with the first puff of wind.
But I've been jumping off well-grazed paddocks for 25 years and as long as you're not jumping the huge stuff, and not jumping on ice (which is never safe), it works fine for lower to mid level work.