The directional yagi is your best bet for strong signal. Signal strength is the inverse square of the distance and that is why the yagi beats any omnidirectional antenna hands down.
The yagi, along with the omnidirectional antenna, is mounted on an extending aluminum pool-cleaning pole (net removed) to the jack bracket. This easily slides up above the roof when needed. I use LTE Discovery to orient the yagi. I use the yagi about 1 out of 10 stops, but then it pays off very nicely. And mounted at the back corner, I need raise the pole only about half the time.
As I recall, the yagi, the pole, and mounting stuff will set you back about $120. I simply connect the cable from the WeBoost amplifier to whichever antenna I want to use (before raising the pole) and cap the other connector. I recommend WeBoost's low loss cable and of course, securely cap the unused connector. It doesn't take much oxidation on an RF connector to start reflecting the signal instead of transmitting it.
The inside antenna/phone is no longer a problem. The bottom of the antenna now has a thin "refrigerator" style strip magnet strip stuck to it. The top of the counter has two thin metal disks (like the ones on a cell phone case for a magnetic mount), that the inside antenna sits on. The top of the inside antenna has the thin shelf/drawer no-skid rubber pad attached to it. I place the phone on the antenna and it stays there. I can hand hold the pair and the no-skid pad keeps the two together.
My system is for 4G bands, but that includes the lower frequency 5G bands The millimeter wave bands are not covered, but the millimeter bands have very short range (but higher bandwidth). If you need 5G millimeter, it is extremely unlikely that you will be anywhere near the places we folks like to go.
I'll post some pictures when we get back - I don't want to blow our 5 Gb, as the PC is using the hotspot.