-Quarterly Offsites where you actually work together in the same room, not strategy sessions. Don't try and come up with strategy during offsites. Get a big hotel conference room in a cheap city (Vegas, Montreal, Orlando) with good internet and sit everyone side by side. Fly in Monday morning, leave Friday afternoon. Do this once every three months for the full team. You get a full week working together. It's better do to longer sessions (like a week) less frequently than shorter sessions (like 2 days) more freuqently. This gets you really synced up with everyone.
-Sunday night executive meetings (Tim Cook does this). Sorry but if you're a startup and you're trying to build something awesome you should expect your leadership team to meet Sunday nights. Audio only phone call is fine.
-Audio-only by default. This doesn't mean "camera off"; that's an awkward format. It means being in a position to have fast, quick audio conversations enables the spontaneous collaboration lost from the physical office in remote work. Audio-only is also more palletable for working late hours. Who wants the camera on at 11pm? But you're willing to voice chat for a sec to work on something. You want to set things up to be able to work around the clock.
-Weekly all hands. Do it closer to the end of the week. I like Thursday afternoon because it tends to maximize attendance. This one's from Skip Schipper, former head of HR at Cisco.
-Make people do live demos in a stage or theater type setting. Make it kind of workshoppy, where there's real-live feedback in realtime as people do stuff. This one's from Steve Jobs.
-AI Meeting Sumamrization is great but you need to make sure its surfaced in a way that the releavant people can get to it.
-Do not pack your calendar with back-to-back video calls. The sign of strength is "calendar zero", not calendar filled up.
-Music. People who listen to similar music tend to get along and bond best. I learned this one from Douglas Hofstader.
-Encourage people to come find you immediately if they need anything. This is the big, fundamental problem with remote. You get stuck, you stop. You must must must get people to take the extra step to proactively find each other so they can keep working at maximum speed.