Hi Michael
Yes, that's exactly what I bought it for. Attention you still need a connection from the card to the router, I bought a DAC from Ubiquiti.

Small addendum, theoretically yes, but my udm pro has a throughput of 3.5 giga, you'll never get through 10

Yep, I have udm pro with spf+ on a spf+switch from unifi and there the pc with this card works tip top. Price performance fits

Yes, it's all OK. You just need to make sure that your router and computer cable are compatible.
In general, the problem is the router.

However, you still need an SFP+ adapter for the expansion card and possibly for the UDMPRO and a fibre optic cable that connects the whole thing, e.g. https://www.digitec.ch/de/s1/product/ubiquiti-unifi-sfp-twinax-kabel-3m-netzwerk-zubehoer-6407933. Regarding the SFP+ adapters - there are different ones from ubiquity. Some can only do 1 Gbit, others can do 1/10 Gbit and others can do 1/2.5/5/10 Gbit.
Or you can use the ASUS XG--C100C expansion card with RJ45 and a cat 7 Ethernet cable of your choice.
I don't think the UDMPRO has a 10 Gbit Ethernet port. So make sure you don't have a pinhole anywhere.

Yes, it works. I connected it with a direct attach cable.