[SPOILER ALERT!]
for portals maybe we can use human created one in ice lab finale (where you can open portal or create resonance cascade) this alien thing do not look like something safe to use as portal
[SPOILER END!]
i think that other worlds can be a bit random but accesing some worlds will be more like suicide but some maybe will have something what will be usefull for player
triffid worlds probaly are great forests, good source of exotic fruits and wildlife but full of triffids, not much threat unless atmosphere is unbreathable (or if breathable it can have some sideeffects too like halucination spores)
fungus probaly have wastelands fillded with fungaloids and local wildlife asimilated by them (maybe hostille?) and maybe ruins of other civilization, largest threat is high (spores cause green house effect) temperature or low temperature (spores block heat and it do not reach surface of planet) other threats are hard to breatch air (spores) what need some air filtration to work or unbreatchable atmosphere
blob? i have no idea, they adapt to evoriment around them and infect local creatures
nether is probaly place where acid is something common, rivers of acid, acid rains, corrosive air…