If you want to go local, then you should go for foundation/matriculation.
In Malaysia we mainly provide geology programmes but yeah it still counts as geoscience since geology is a part of geoscience and you get to choose your own specialization during your final year in degree. Local universities such as UM, UKM, UMK and UMS offer geoscience/geology programme for undergraduates.
So if you prefer public, then you should apply asasi UiTM/UM (bumiputeras only) or matriculation. But personally I would suggest matriculation because they actually do lower your grades for your finals (like SPM) and hence better chances to score better GPA. I also heard you get to repeat your test if you failed. Well, on the other hand, if you think you can cope with stress (different kind of stress in asasi) and you trust yourself in securing excellent carry marks, then I'd suggest asasi UiTM/UM.
But you need to know one thing for sure if you want to go for public universities. You still have to fill up your UPU (again, I know!) for your degree. You're going to compete with students from matriculation, asasi UiTM/UM, diploma and STPM. So it's your decision to choose which path hold higher possibilities for you to pursue geoscience.
If you're willing to challenge yourself (financially), you should go for private. We have UTP and Curtin University. They offer foundation and undergraduate programme for petroleum geoscience and geology respectively (almost the same thing but still, the same). Also, they have lower requirements in terms of academic performance compared to those in public universities. If you're worried about scholarships, don't be. There are many scholarships for geoscience students that people barely notice. We have Shell, Petronas, Tasmania, JPA, etc etc etc.
All in all, every choice has its own pros and cons. So, choose wisely. And most of all, stick to your choice until the very end.
Just to add some note: if you aim for UM for your degree, you must score CGPA 4.0 (I add the 'must' to scare you aha! jk but yea UM is probably like the most popular kid in school so you gotta aim high to secure your place there). If you aim for other universities besides UM, try to get at least 3.5 and above. Just to play safe.
Also extra note: If you want to go overseas, you can take A-level. But honestly, you still can get to study overseas using your pointer in matriculation, foundation, etc. Good luck.