Perhaps you can try DECT NR+ the new reincarnation of DECT and also backward compatible with the original DECT [1]. It can also do roaming.

It's under 5G standard but for non-cellular connectivity that means you can use it without base-station like Wi-Fi direct. It's geared toward IoT but its data rates are from 1 Mbps up to 1.3 Gbps depending on the operating frequency and the type of modulation being used [2].

[1] DECT NR+: A technical dive into non-cellular 5G (30 comnents):

https://news.ycombinator.com/item?id=39905644

[2] Technology: DECT NR+ [pdf]:

https://www.vdma.eu/documents/d/group-34568/technology_dect-...