You can stick to 802.11r only by lowering the transmission power and have all the APs on the same channel, in my tests it ended up switching much faster than K/V. (~75ms)

On iOS, equal channel with correct ESS will switch liberally. On Android 14+ with Broadcom chip it will start conservative, then switch liberally after the first poor signal switch-over event, up until disconnection.

Android (Pixel/Moto) will never switch (even with K/V) on large network activity, only VoIP/video call. It depends on vendor implementation. I use "dp.logcatapp" log reader while roaming, "ModemStats" shows the score/load and is used on most vanilla builds.

Samsung is known to push protocol support early: 802.11r in 2013, 802.11w 2015, some models do not use Android's default connectivity manager.

To add, WPA3 with 802.11r is known to have issues on Apple hardware before 2021 on all iOS versions, many Android devices, especially smart TVs don't support it, will not connect or are unreliable (protected beacon frame), can be searched in buried report results at OpenWrt forum mega threads and Ubiquity. WPA2+FT and forced MFP with a long password is a safe alternative.

802.11K/V is more suitable for campus and load balancing, tuning it based on RSSI and station metrics is very difficult, enterprise hardware rely on network traffic and air time.