I’m aware that marriage among royalty in the Medieval period (and on either side of it) was used primarily as a means of solidifying power, and as such children were married to each other or to much older or younger individuals, but assuming they were of-age for the time or older before they were married, would it have been common for male heirs to enter a marriage with their virginity?
I know it would be notoriously difficult to keep a record of such things but I’m hoping there are some kinds of records of general consensus on the subject, whether among the lower or upper classes of the time. How would this be viewed by the general population of 15th century England?
Generally, kings wed while still princes, with a few exceptions. Unless there were a particular reason to note it, there wouldn't have been an official record of if a prince was a virgin before marrying. For example, if a prince did wed young and made some faux pas because he was a virgin that made for good gossip, there might be a record of that. That still wouldn't be an official court document, but it could show up in a personal letter for example.
Girls and boys respectively were considered of age to marry and consummate at 12 and 14, though it was tasteful to let the girl wait till 14. Theoretically, nothing prevented a young prince from having pre-marital sex, even though Catholicism frowned on it.
Henri II of France married Catherine de Medici when they were both 14, and he had a mistress by the time he was at least 16. So sex for pleasure or purpose at a young age wasn't abnormal, but there is no surviving record of whether he was a virgin or not, despite being observed during the act of consummation.
If royals generally married later in life, it would be easier to presume the men had been sexual prior to marriage since taking at least one mistress was common. Between age of consummation rules and the busy educations of heir apparents, it's reasonable to presume virginity is more likely in a royal child groom.
The virginity of the bride was the focus of the people, the virginity and sexual fidelity of the heir apparent was a relative non-issue unless it got out of hand. For example, a monarch like Edward II of England who pretty much ignored his duties to dote on his lover.
That being said, while focus for criminalizing underage sex rested more on girls, if a prince of say 8 years of age was caught having 'sex' [being abused] there would be a big problem. The woman would be seen as an abuser who'd taken advantage, and it would be trouble for the caretakers who'd let the prince out of sight long enough for the offense to happen. In that case, the people wouldn't really think of his lack of virginity, but that their future king had been violated by a sinful woman. I'm not sure offhand if it falls under any treason laws, those could change from monarch to monarch, but it seems it would fall under harming a royal person.
Summarizing, the younger the prince/king the more likely they were to be a virgin at marriage. The people were worried about bridal chastity, not groom chastity.