IPv6 RA/DHCPv6 support for nspawn?

[ValdikSS <iam@xxxxxxxxxxxxxxx>]

Greetings, everyone.

I'm running systemd v250.4 (Debian 11 backports) and can't find a way to 
automatically configure IPv6 access inside nspawn (machined) container, 
either with or without NAT.

Despite DNAT and MASQUERADE functions for IPv6 being supported since 
v248 and work fine, and networkd's 80-container-ve.network file includes
    IPMasquerade=both
by default, there's no records of ULA IPv6 address range to be served 
for the containers.
If the range is added to the .network file, the IP address from it is 
getting assigned to the interface of host network but not announced to 
guest using RA, at least I tried multiple configuration settings and 
can't get it working.

I ended up configuring IPv6 statically on both host and container, which 
is inconvenient. I found no bugs on bugtracker for this issue. Could it 
be I'm misconfiguring something, and IPv6 RA/DHCPv6 server support 
present in networkd and work for nspawn'ed containers?

P.S. please include me in cc, I'm not subscribed to every email in this 
mail list.