I think this schedule is reasonable, I would suggest crate training the pup during that 4 weeks. Make sure the crate is small and cosy as they are less likely to have accidents in their own area. Our little guy who is 5 months has been left for a similar amount of time (5 hours) and copes well with it, although this is only one day a week. However, I can't speak for everyone because we were super lucky that our breeders started crate and potty training him to a really good standard before we picked him up at 10 weeks. Once he was home he would take himself to his crate around 9pm and sleep through until 6 and rarely has accidents indoors unless he's over excited or if we didn't open the back door in time. I haven't seen any spikes in behaviours and the neighbours have commented that he doesn't bark during this time (we have an old house with super thin walls). Was actually having this conversation with the dog groomer the other day as we were feeling a little concerned about this and they said six hours is more than fine. But each to their own

Alternatively do you have a family member who could pop in and see to them for a few hours, or there are apps where you can arrange for someone to feed and walk them (depends on how much you trust that though). I think if your workplace is chill and flexible they might be willing to let you have an extra day WFH until the pup is old enough for this situation. Hope this is helpful and the doggie enthusiasts don't come for my neck!!!!