How do I get the xgs-pon module individually? I already have a 5590 and am in the process of switching.

Not myself, but theoretically it should be possible since it has recently (01.07.2023) been officially certified: https://www.swisscom.ch/content...

Under Internet provider, select Swisscom FTTH DHCP and enter the modem ID of the FritzBox 5590 XGS-PON under ONT installation ID.
Under swisscom.com/access enter the fibre optic socket number and the slot (usually no. 2). Then it works with Swisscom.

The FRITZ!Box 5590 XGS-PON has been unlocked on the Swisscom XGS-PON fibre network since 23 May 2023. Apparently the 5590 XGS-PON also runs with Wingo.

Unfortunately, we do not have our own experience in this regard. We recommend that you start a discussion. Experience has shown that more customers respond there than to a single question.