What my team does, is every 1 or 2 months we would all go to work at the office for 1 day (not mandatory of course, but people usually like to come), at the end of which we would all go to a really nice restaurant, and order anything we'd like, paid by our boss. 90% of us are WFH, and I find this works really well and helps with bonding.
You could block internet access for your browser. There are a lot of apps that let you do that (and in some cases I think you can also manage internet access in your settings).