Are solid core or solid roundhead or FMJ or whatever the fuck they called, shaped like a dick bullets better than hollow points for self defense?
if you mean copper solids, they tend to be light weight and have much higher velocity than is typical for the cartridge. they tend to not deform much when striking a target, and cause pretty nasty bleeding, tearing wounds. they are generally also legal in those jurisdictions that prohibit expanding bullet designs (because they are non-expanding).
edit: if you mean full metal jacket (FMJ) bullets, they are thin gliding metal over a (usually) lead core and are very inexpensive to make. they will generally penetrate objects further than jacketed hollow points (JHP) but non-fatal hits are usually not particularly deadly albeit painful. many people will tend to freeze up and fall over when shot, regardless of hit location due to the sudden shock and incoming pain, but someone who has enough of an adrenaline or similar chemical boost can ignore non-fatal hits (non central nervous system, CNS, or non "man-stopping" hits) and fight back even when bleeding to death. be sure of your shot placement.
And is it also okay to mix the bullets as my current ammo can is too small to hold boxes so I said fuck it and mixed in all my available rounds of 5.56 and .223 with each other.
if you have a firearm where the cartridges are interchangeable (like mixing .38 Spl into a large bag with .357 Mag) then no, it doesn't matter. if you have a firearm where it does matter (.45 ACP and .45 Super in the same bag) then this is a bad idea and may result in injury, damage, death, or a combination thereof.
Also I noticed the hollow points cost more as well per bullet compared to a regular target practice bullet.
more complex to manufacture unless reverse drawn, which requires specialized machinery. i've looked into manufacturing my own JHP ammunition on a small scale, but it's not economical without mass manufacturing and a bank account to absorb short term losses.
an extremely unpopular time
many new gun owners bought out of fear of either never getting a gun, or needing one and not having it. they are not "committed" to gun rights, and political bedfellow can sway people to willingly give them up for a political/ideological reason, or that they would be risking their life/livelihood for something they only just acquired and haven't owned for very long.
i fully expect half of the millions of new guns to be lost, stolen, or sold back into the market in short order because the new owners are not "gun people". they lack the culture or the drive and instead made an impulsive decision based on a combination of fear and "if they are doing it, we need to also, because we are warriors in our political tribe".
there are precious few new owners i've encountered (regardless of their politics) that see guns as the modern way to exercise a fundamental human right to self-defense. they are toys, pacifiers, and/or magic totems that make "bad things" go away and when an adult promises to do so for them, to relieve them of the burden of responsibility, they can be just as easily given up without any remorse.