Looking for advice, not sure if this is just puppy blues or not!

Basically me and my partner are both stressed and extremely tired ,also worried that we are not the right fit for the dog we adopted.

we have a 1 year old collie and hes really loving and fun, we got him at 8 weeks from a shelter. ive been finding it really hard recently like theres just no let up or rest. we where not aware at all that he was a working breed we where getting which is obviously on us, and rehoming is the last option we want to do as we love him to bits but we are struggling with alot of issues on top of both working full time and 2 kids.

1. for context usually one of us is working from home and i have my kids from ex half the time. the times the kids are with us, im already up at 6am to get organised for school etc , the days im in office, im not finished and home and done with homework until 6 at best, before dinner can be started and a walk considered so my partner usually wakes early those days to walk him. if im home and SO is in office, i walk him during work hours twice , obviously this isnt ideal long term and im lucky work is quiet at the minute, but other wise im still up early and home late with kids.
2. the weeks i dont have the kids used to be when we recovered a bit of lost sleep but its now when both of use take turns getting up early to walk him in the morning and one of us after work.
3. the walks are torture, always lunging to people or other dogs in excitement, prams as well or scooters/bikes are a trigger, seems to ignore cars and vehicles. pees on people when theres visitors.
4. we've put alot of effort in with training and feel so defeated that only some things have stuck, i do herding games with him that ive seen online , food puzzles , frozen kong treats, and he still seems unfulfilled with 2 walks a day and being run around the garden we have which is quite big too even for him he gets a really good run around there.
5. he seems to just not have an off switch, if i try to work in the kitchen with him to give him a bit of company he keeps barking at me to let him out to garden, i dont anymore as he justs eats stones and digs massive holes and then drags it all in when im not with him. half the time crap is coming in too, then i need to get out disinfectants and try and wash him/the floor.
6. im brushing him multiple times a week and hoovering but hairs are still ending up in our food, there isnt anywhere else in the house we can keep him than kitchen.
7. he isnt getting along with our older cat either, the cat is wary of the dog, but seems interested in him. always trying to see what hes upto or watch him in the crate. but our dog keeps trying to herd or chase the cat. we've tried a lot of different ideas to try get them along but our dog just wont take and its been so long now. as a result we have a very closed off house and constantly closing doors.
8. we cant relax with dog in living room since he just wont rest unless hes in the crate, but also the cat is in that room. it feels like its a cycle of just get him tired so we can rest but in reality we have piles of other stuff to be doing too.
9. he barks just to get out of the house so often, even in the middle of the night, we are conscious of bothering neighbours, and him needing to pee or poop, but so often he just goes and immediately digs for rocks in the garden. we find it hard to tell the difference between barks for toilet break and just from boredom/wanting to get out.
10. i'd love to say we make it work but if im walking him in work hours half the time it isnt really working, i think we're barely keeping it together but still nearly always giving him am and pm walks.
11. theres some issue with his eyes also that vet recommended we get cover for, we did but are worried this could be a barrier rehoming him. dont want to hide it but disclosing it could hinder anyone adopting him.
12. we dont have time for each other anymore either,and definitely both feel like we need rest /cant keep this up, i find myself walking him because i know its what he needs despite dying for a few minutes rest myself and im sure my partner is the same. i dont even have time to go gym by myself or do any of my own destressing / unwinding hobbies.
13. we feel like at this stage what was once lovely and happy experience is just alot of stress, we're putting so much money and time in and feel that we cant keep up and he still doesnt seem fully happy or fullfilled himself. im getting to the stage where i dread having to deal with him or see him as a chore and im not happy with the person i am thinking this way.

i guess we are just looking for ideas for help as we both dont want to give him up? would some behavioral courses help with dog trainers? we are planning for a child also and worried even with behaviour training that we just wont be able to manage him and a newborn, but no guarantees that will go anywhere either with our ages, so we dont want to go down that route if not needed.

i know some of what to expect in the comments but i am looking for advice from people who where in a spot like us, and made it through it with their dog?