From the rules, it seems that an initiative check is just an ability check. There are numerous effects that give Disadvantage on ability checks, and some that give Advantage.
I don't see it called out anywhere specifically, so should I assume that you can have advantage/disadvantage on these checks as normal?
Some examples; using inspiration to get Advantage on an initiative check, or getting Disadvantage if you're poisoned or exhausted.
(I ask because I'm used to initiative checks being special cases, and also because the Alert feat gives a flat +5 to those checks, when I'd expect it to grant Advantage if that's possible. On the other hand, it doesn't actually say Initiative is anything special.)