Is your 2 year old always at home or does he go to nursery some days?
I have a 2 year old (soon to be 3) and a 10 week old but toddler is in nursery 3 days a week which is a godsend. And there's absolutely no way she'd go in a playpen at this age!!!
The other days when DH is at work it's so much easier being out than at home. Baby in pram or carrier, and take toddler to park/picnic in the woods etc if it ever stops raining, or indoor playgroups which are usually quite cheap.
Obv avoid going to those huge soft plays where you always have to climb in with them but see if you have any gymnastic clubs near you that often have open soft play style sessions which are all on the floor and don't involve climbing up things, they are so good and perfect if you have baby in carrier as you don't have to do too much.
If you have to stay home then do a raid of The Works or Hobbycraft or even FB marketplace for cheap crafty things, sticker books, anything that will keep them entertained for a bit. We have a conservatory where all this crap lives and we leave some stuff out for toddler to go wild with, minimal supervision needed.
But also I do tend to resort to some TV time as needed, it's not the end of the world!
For me the biggest stress is trying to get ready with no one else to look after the kids (most of MN seem to be able to get ready in 5 mins with 30 second showers but that's definitely not me) so I make sure I get up, showered and presentable before DH leaves. The odd times I've stayed in pj's most of the day I just feel horrendous, I'm not saying it's a bad thing to do at all but it makes a massive difference to how I feel that day.
Other stuff you can do when toddler is in bed and DH is back- make sure house is toddlerproof, prep meals for next day, clean enough to make sure you aren't mentally overwhelmed with how much there is to do. Before #2 came along I made sure we'd decluttered the house as much as possible and that absolutely everything has a home so that I can just chuck it in at the end of the day. Things like don't have more clothes than wardrobe space (this used to prevent me putting laundry away so it would just stay on the drying racks or in baskets for ages, so I did a huge clearout and was ruthless). OK there's a couple of big boxes of 'stuff' in the garage that I need to sort one day but it's not important right now and doesn't need to be out.