Ljubljana, Slovenia to Pula, Croatia

I just looked on Rome to Rio and found answers. Bus, train.
Investigate that.

Ljubljana – Rijeka by train
https://reiseauskunft.bahn.de/bin/query.exe/en?start=1&existOptimizePrice-deactivated=1&REQ0JourneyStopsS0A=1&S=Ljubljana&REQ0JourneyStopsSID=A%3D1%40O%3DLjubljana%40X%3D14512940%40Y%3D46058687%40U%3D81%40L%3D007900003%40B%3D1%40p%3D1674067046%40&REQ0JourneyStopsZ0A=1&Z=Rijeka&REQ0JourneyStopsZID=A%3D1%40O%3DRijeka%40X%3D14430339%40Y%3D45330138%40U%3D81%40L%3D007800013%40B%3D1%40p%3D1670274153%40&date=Do.%2C+23.03.2023&time=08%3A00&timesel=depart&returnDate=&returnTime=&optimize=0&auskunft_travelers_number=1&tariffTravellerType.1=E&tariffTravellerReductionClass.1=0&tariffClass=2&externRequest=yes&HWAI=JS%21js%3Dyes%21ajax%3Dyes%21#hfsseq1|cu.029031189.1675967451
2 connections per day, about 3 hours

Rijeka – Pula by bus
https://www.buscroatia.com/routes-search/?dSn=Rijeka+%28HR%29&aSn=Pula+%28HR%29&d=2023-03-23&dS=1124&aS=1079
Many connections per day operated by Arriva and Brioni, about 2 hours.