My house is old and has stones walls up to 120cm, including the inner walls, so I have to have access points is nearly all rooms.
I never had a true seamless roaming experience. Today, I have TP-Link Omada and it works better than previous solutions, but it is still not as good as DECT phones for examples.
For example if I watch a twitch stream in my room and go to the kitchen grab something with my tablet or my phone, I have a freeze about 30% of the times, but not very long. Before I sometime had to turn the wifi off and on on my device for it to roam.
I followed all Omada and general WiFi best practice I could find about frequency, overlap... But it is still not fully seamless yes.