Hi, yes - get out of the house every day for an hour's walk, stay in quiet streets and be prepared to avoid people if you encounter them. Go even if it rains. If the baby hates the pram use a sling. Walk as fast as you are able to so you get a bit out of breath, put your phone in your pocket and ignore it.
Exercise, daylight, fresh air is hugely beneficial, it is free and hugely underestimated. With my DS it saved me (vs experience with DD1). Don't worry about covid19, just don't loiter, avoid people and don't touch anything eg park bench.
Next bit of advice, see if your local NCT group on Facebook or other community or mums group is holding online coffee chats. Speaking to other mums usually helps.
To state the obvious, a lot of mums feel like you and usually it is mild pnd, there's no bond, it's not what you hoped and expected, you're too exhausted to be the mum you want to be, you're so empty you feel you could just give up (except deep down you know you can't so you feel trapped too), your OH doesn't get how you feel and that annoys you...and so on.
See if your Oh can have the baby for several hours every other day. A break to do anything other than be a mum would really help you.