Broadband Internet & ISP Recommendations?

Our Community Fibre went down early Monday morning and still isn't back up.

The problem is a fibre box on our telegraph pole so it affected four other neighbours. Engineer came out today and could only reconnect two on the other side of the street, so there are three of us still waiting to be reconnected. The engineer had to pass it to another team and with the weekend it's looking like it will be Tuesday earliest and probably Wednesday. Hopefully. Not great.

I had to WFH yesterday as it was my first day back from holiday and there were no desks left in our office. Had to do some Teams calls and got through 6Gb of data using my phone as a 4/5G hotspot. Had to WFH again today to collar the engineer as neighbours had visits booked today but ours wasn't due to be until Monday, but I've got no meetings and am managing to do mostly offline work so I should be using quite a bit less data.

Our next door but one neighbour has Vodafone over Openreach as a failover and we've been trying to pick up his WiFi with no joy so far.

The whole thing has made me realise we rely on the internet for so many things (especially as we've done the smart home thing, although I'm trying to make it less cloud dependent) that we really need some sort of failover too.

We've got Unifi everything, including a USG which has a second WAN port and does failover/load balancing, so their U-LTE-Pro would make sense, but it's only 4G and I don't think it makes sense to invest in anything which isn't 5G capable in 2023.

I basically want something I can put a SIM in and connect to the USG, but at this point if it was a fair bit cheaper I'd consider a quick fix too.

Any ideas? Next door but one neighbour would be happy to split the cost of a 4/5G failover if we can work out how to bridge our two networks as he'd prefer over the air to cabled as a backup.