I also understand IT security is dramatically complicated by user's working on their private network connection or even private client devices.

As otherwise mentioned, it's actually straightforward.

I work in the daytime on some pretty well-secured stuff; not "secret squirrel" but "people data" stuff. There's a LOT of forms to sign, and they want to ensure you're not working on a shared patio but in a real, dedicated office space that is ergonomically optimal and private, with a few other rules, but the effort that started as a panic on COVID day 1 proved workable and they're going with it. They sold the offices in the dank ugly building. And this org is actually insanely cautious and works with cautious entities, and even they could work it.

At night I work for a different company on different shipped gear... and a KVM switch to go from one set to the other. They're all segregated and secure, and the night job I've had for 22 years with only two invites to fly down to the office for a visit in that time. Barbecues, actually.

I have a lovely view of the river.

It works. You have to be sensible and secure, and then you're golden.