The tone of your post suggests your relationship is generally okay. Starting from the assumption that he isn’t a terrible person (I know this is an unusual assumption on mumsnet), this could be the start of a really useful conversation. especially with another baby on the way, it’s good to talk about what you both need. As long as it is both of you, not just his needs.
You could usefully discuss why he finds time with your child hard. It sounds like his expectations are wrong for this age - he thinks he should be able to do his own thing and just keep an eye on the child, but toddlers need lots more interaction. He can’t just opt out of a childhood phase, he has to figure this out regardless of how much time he is the designated parent.
Personally, with a 2day vs 5 day working week I think 70:30 parenting split isn’t unreasonable - you’re probably already there tbh. In your shoes I’d agree with him that he needs time to rest at the weekend but push for chunks of a few hours that he is fully in charge of your child and fully engaged. No trying to get something else done, make that time really count. But it’s only eg a few hours each day at the weekend, an hour each week day, and he can plan for it. Basically, I wouldn’t argue the quantity so much as the quality.
As others have said, you should point out that you also need time off. You are doing the bulk of childcare during the week, you need some chance every day and a longer period at least once a week to do your own thing. Both of you need some protected down time.
It’s also maybe an opportunity to talk about buying in help, if you have the cash. Getting a babysitter and spending time together can also help a lot, or even if you can’t go out you can decide to have a date night at home after the kids are asleep. Again, push for quality more than quantity. A couple of hours a week without distractions spending time together and making a proper effort to connect.
parenting is hard and opting out is not the solution.