How to handle security group rules for an SG with count condition

Terraform Providers AWS
1

Hello,
I would like to create a security group with a count condition like this:

resource "aws_security_group" "sg" {
  count       = var.autoscaling ? 0 : 1
  name        = "${var.env}.test.sg"
  description = "test sg"
  vpc_id      = var.vpc_id

  tags = {
    Name            = "${var.env}.test.sg"
    ResourceType    = "sg"
  }
}

When autoscaling is set to false however I cannot handle the corresponding SG rules that I load with for_each like this:

resource "aws_vpc_security_group_egress_rule" "sgrules_out" {
  for_each = { for rule in var.sgrules_outbound : rule.rule_name => rule }
  cidr_ipv4         = each.value.cidr_blocks
  description       = each.value.description
  from_port         = each.value.from_port
  to_port           = each.value.to_port
  ip_protocol       = each.value.protocol
  security_group_id = aws_security_group.sg.*.id

  tags = {
    Name            = "${var.env}.test.sg"
    ResourceType    = "Infra_Network"
  }
}

sg.tfvars:

sgrules_outbound = [
  {
    rule_name   = "test"
    cidr_blocks = ["192.168.1.0/24"]
    description = "test"
    from_port   = 1500
    protocol    = "tcp"
    to_port     = 1500
  }
]

Error I get is:

Error: Incorrect attribute value type

  on sg_efs.tf line 32, in resource "aws_vpc_security_group_egress_rule" "sgrules_out":
  32:   security_group_id = aws_security_group.sg.*.id
    ├────────────────
    │ aws_security_group.sg is tuple with 1 element

Inappropriate value for attribute "security_group_id": string required.

Is there a way to handle these rules when the SG’s condition is false and therefore it shouldn’t create it? I know count and for_each are not supported together, unfortunately.