Is it possible to transfer btc from my btc wallet to btc segwit wallet?
To answer this question, you have to know that there are two types of SegWit addresses...
The answer to this question (which by the way is: YES) is completely independent from the type of segwit addresses..
It is
always possible to transfer btc's from a non-segwit wallet to a segwit wallet.
...While native SegWit "bc1" addresses can only send and receive from other native "bc1" and SegWit nested "3" addresses and cannot send or receive from legacy addresses.
This statement is illogical and contentual wrong.
SegWit was implemented as a soft fork. If somehow it wouldn't be possible to send/receive to/from 'old legacy' addresses, this would not be called backwards compatible.
Backwards compatibility is a requirement for a soft fork.
Additionally, not every address starting with a '3..' is a nested segwit address (P2WPKH/P2SH).
Simple multi-signature addresses also do start with a '3..'.