Swami,
 
This could be understood by visualising the time during creation. First there is only Narayana and no other thing exist (Vaikuntam exists as Vishnu’s padam so there is no other external thing in the cosmic space). Then when the time for creation arises Narayana starts to divide moola prakriti into many sub parts. Let’s visualise each sub part as a bubble. Bhagavan enters into each of these bubble and begins the creation activities like creating planets, Brahma, etc i.e. a universe is created in each of these bubbles. Refer image below

Now each bubble is nothing but moola prakriti and since he enters each spherical bubble and begins the creation activities, it is said as his womb. 
 
Now to the question of can a Purusha have a womb. Purusha does not have a womb. Even bhagavan also does not have an internal womb in his Divya Mangala Shareeram.
But due to such a creation phenomenon, bhagavan refers to moola prakriti as his womb.  
 
However, interesting to note that there are representations in material world and beyond for all possible statements that we can write. Since bhagavan said something to be his womb, there is a very rare disorder occurring in males where they develop a womb also along with the normal male shareeram. You may read this news here
https://thelogicalindian.com/amp/lgbtq/mikey-chanel-trans-teen-pregnancy-24922
 
The bubble concept that adiyen had explained is likely in Srimad Bhagavatham. Adiyen does not know the exact chapter or lines as in the book.
 
Kshamathvam for any errors and credits to Velukkudi Swamy
 
Adiyen
 
 

Srimathe Rangaramanuja Mahadesikaya Namaha

The whole idea of Azhwar(s) is to achieve

“Naichya AnusandhAnam”

“Dasa BhAvam”

So they adorn the character that deems fit

Someone told me “Athma” in Sanskrit is referred as male only.

Other perception is we are pathni & he is pathi.

Dasanudasan