Exo planets do still appear randomly from time to time.
This is the exo announcement post.
For their materials and depending on the exo tier, they can have lucent gems and kindling seeds/plants in addition to petroleum and resin. This is plus all the normal stuff you find on normal worlds. Colors are random but lucent gem worlds do seem to have specific palettes like lighter colors for blink worlds, reddish colors for umbris, etc.
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