I also need some advice.

I am shifting my thinking a bit, it may not be as personal as wanting to undermine your authority but rather that he has a different parenting style perhaps due to his own upbringing, he may see your approach as too restrictive and demanding.

You are in the situation so you are best able to determine motivations etc.,

Toddlers are known to go through a phase of asserting their independence so bear that in mind, it is important to provide choice and a sense of their own control.

I truly believe it's a bit of both the undermining as well as the guilty parenting. He is a very "old school" man when it comes to who is in charge in the house.
It may have started as guilty parenting and then evolved into the former. Either way it's a problem simply because of the mixed messages it sends to our son.
I am simply asking for compliance in the things that are necessary for normal life. Things that HAVE to be done. I am not asking for anything stringent or rigid.
Imagine if you will...a toddler without a bedtime that watches shows on his tablet until he falls asleep, if it's taken away he cries. Then he is too sleepy to get up in the morning and has to be woken up twenty times and taken to the bathroom to brush his teeth to which he will protest fifteen more minutes. After throwing himself down on the ground and running to find his dad they curl back up for hugs and if you are lucky in another ten minutes he emerges to tell you he will brush it later.
At breakfast time he wants chips and refuses to eat anything else . In the spirit of compromise you offer some chips along with what was prepared. He eats the chips and very little else. You know he will be hungry before snack time in school.
Shower and dressing time is an agonizing 50 minutes or more full of interruptions and "I don't want to" tantrums broken up by " why do you have the kid crying so much?" And "Daddy save me", "Jesus save me I don't want to"
And of course multiple breaks for " comforting".
Once dressed you instruct him to sit and wait for a few minutes while you ensure the house is locked up and the appliances switched off and cameras and alarm are on and set, but by the time you get that done he has gotten into something that gets his uniform all messy and you've got to change him before school.
You arrive at work in time by a hairs- breadth and just sit in the office for twenty minutes to catch a break.
Now I know parenting isn't easy, and lots such scenarios exist the world over, but the difference is "are the parents in it together?"
It's solely my responsibility to prepare meals and do housework and do the necessary things for the daily functioning of our home and the people in it, shopping, laundry, bath times etc.
I feel like I just can't go on when my husband quite carelessly refuses to lend even his verbal support with our son to make things work.

Also let me add that I am as doting and caring as the next mom who waited five years for her first and only child.
Because I have more of a stable, year round job, I am the one that splurges on the expensive toys and presents and big birthday parties. I am the one that loves to order the cute outfits and plans the trips to kid themed events and parks.
But I do it from a different place not from a place of him demanding it by throwing a tantrum or trying to get his way by crying about nothing.
I honestly feel that the lesson our toddler is leaving with is that the way to get what he wants is to throw a tantrum until the other person gives in.

Discipline. take away things so he can get the message. Spare the rod spoil the child means progressively disciplinary action. Not beat him to death but making a point for him to obey. The good news is as he grows older he will be more drawn to you. But respect is earned not given.

Hello sister. I'm not judging anyone or criticize anyone. Ephesians chapter 6. Its parent's duty to raise children as Christian, and teach them fundamental of God's word. Paul wrote Corinthians chapter 7. About marriage. Both Christian. Or one Christian, and other non Christian. This can have serious consequences for spiritual development and growth.

I'm offering sound advice. In 2018, I moved away from narcissist. He was interfering with my spiritual growth. And I went through psychological abuse and emotional abuse.

Mark chapter 9:47. And if your eye causes you to sin, pluck it out. It is better to for you to enter the kingdom of God with one eye, rather than two eyes, to be cast onto hell fire.

Repentance is important. And genuine faith. Must be Doers of the word, those who do of God. Empty religion is lip service.

Isaiah chapter 65. I have spread my hands all day unto a rebellion people, which Walk in a way that is not good, after there own thought's.
Those who refuse to raise children as Christian, are problem, and could be offense to the spiritual welfare of the child. Those involved in traditions of men and false doctrine, are detrimental to you.

If something or somone is causing you or your child to sin, its grounds to move away.

It's your decision.
Peace.