As the title says, how would one go about it or is it not possible at this time?
Most probably not. You can get a Shifter (to a degree) by picking up any martial with a druid multiclass dedication, a few wild order feats, the feat for the specific order spell and that is wehre your path ends
partially because there is no swarm polymorph (that I am aware of)
That is unfortunate.
Thank you though.
And now I want a Swarm Eidolon just so I can Meld with it.
Yeah...
Do you think that the shifter class will be redone for 2E or would have be reduant?
Also don't they have the skinwalkers in 2E and you can choose a vermin shape I thought.
While you probably can't become a full swarm shifter, we do have the Swarm Domain, as well as some spells like Vomit Swarm.
The domain might be a way to get something close to it, but the lack of ability to attack while in swarm form is a bit of a deal breaker.
I'm looking forward to Book of the Dead to indirectly help with being a swarm-being because, if it balances well, that'll give us some framework for eventually becoming things like a Worm that Walks.
I do like Worm/Swarm that Walks...
Is Book of the Dead specified to have swarm related things in it?
Also, I did some looking and using the cleric archetype I wouldn't get swarm form until 16th level. So that doesn't work.