The story so far:

To get to a working ufo binary you have to build it against SDL2 (built with --disable-video-opengl) and then run it in either 16 or 32 bpp mode - 24 bpp doesn't work. Could it be related to the internal alpha-blending in Mali?

In case there are two copies of libMali.so in /usr/lib/arm-linux-gnueabihf/mali-egl and /usr/lib/arm-linux-gnueabihf/ make sure the latter one is being linked in - otherwise you'll end up with a "Mali API driver/userspace version (600 vs 401) mismatch error.

The display problems are as follows (all screenshots come out black):
* the splash screen is completely white
* the start screen is fine
* 3d geoscape - white background, the rest normal apart from the 3d objects on the surface which are completely white
* 2d geoscape - all white except for the base markers (arrows)
* base screen - a fully built-up base displays fine, empty spaces - white
* soldier equipment and soldiers themselves - white silhouettes
* battlescape - alienbase: colours somewhat normal except for the soldiers and their portraits which are just white outlines again, other maps' colours: whitish-pink

So in short probably all the GLES rendered parts are just white spaces.

And the video startup output:

------- video initialization -------
* I: SDL version: 2.0.4
* I: found 1 display(s)
* I: current desktop mode: 1280x1024@59Hz (SDL_PIXELFORMAT_RGB565)
* I: video driver: x11
* I: available driver: x11
* I: available driver: mir
* I: available driver: dummy
* I: driver: x11
* I: setting mode 8
* I: try to get display with 1280x1024
* I: disable multisample buffers
* I: set swap control to 0
* I: 1280x1024 (fullscreen: no)
* I: got 8 bits of stencil
* I: got 24 bits of depth buffer
* I: got double buffer
* I: got 5 bits for red
* I: got 6 bits for green
* I: got 5 bits for blue
* I: got 0 bits for alpha
* I: got multisample disabled
* I: got 0 multisample buffers
* GL_VENDOR: ARM
* GL_RENDERER: Mali-450 MP
* GL_VERSION: OpenGL ES-CM 1.1
* GL_EXTENSIONS: GL_OES_byte_coordinates GL_OES_fixed_point GL_OES_single_precision GL_OES_matrix_get GL_OES_read_format GL_OES_compressed_paletted_texture GL_OES_point_size_array GL_OES_point_sprite GL_OES_texture_npot GL_OES_vertex_array_object GL_OES_query_matrix GL_OES_matrix_palette GL_OES_extended_matrix_palette GL_OES_compressed_ETC1_RGB8_texture GL_EXT_compressed_ETC1_RGB8_sub_texture GL_OES_EGL_image GL_OES_draw_texture GL_OES_depth_texture GL_OES_packed_depth_stencil GL_EXT_texture_format_BGRA8888 GL_OES_framebuffer_object GL_OES_stencil8 GL_OES_depth24 GL_ARM_rgba8 GL_OES_EGL_image_external GL_OES_EGL_sync GL_OES_rgb8_rgba8 GL_EXT_multisampled_render_to_texture GL_OES_texture_cube_map GL_EXT_discard_framebuffer GL_EXT_robustness GL_OES_depth_texture_cube_map GL_OES_vertex_half_float GL_KHR_debug GL_OES_mapbuffer
* OpenGL version detected: 1.1GL_ARB_multitexture not found
* Overriding GL_ARB_multitexture - it is always present in GLES
* found GL_OES_texture_npot
* using GL_ARB_texture_non_power_of_two
* GL_EXT_texture_filter_anisotropic not found
* GL_EXT_texture_lod_bias not found
* GL_ARB_vertex_buffer_object not found
* Overriding GL_ARB_vertex_buffer_object - it is always present in GLES
* using GL_ARB_vertex_buffer_object
* max vertex buffer size: 16777216
* GL_ARB_fragment_shader not found
* GL_ARB_shading_language_100 not found
* GLSL shaders unsupported by OpenGL implementation.
* found GL_###_framebuffer_object
* glFramebufferTexture1D### not found
* glFramebufferTexture3D### not found
* using GL_ARB_framebuffer_object
* max draw buffers: 1
* max render buffer size: 4096
* max color attachments: 1
* max supported vertex texture units: 0
* max supported lights: 8
* max texture units: 8
* max texture coords: 8
* max vertex attributes: 0
* max varying floats: 9010128
* max fragment uniform components: 9010128
* max vertex uniform components: 9010128
* max texture size: detected 4096
* Using medium resolution globe textures as requested.
* not using GLSL shaders
SDL_ttf version 2.0.12 - we need at least 2.0.7