You mostly have your answers already.
To #2-3, I'll simply add, Homepods are not really meant for this purpose. Yes, they can be used this way but they are really meant to to mono or (paired) stereo speakers for
music/radio.
A 65" screen just about shouts "home theater" and you will not find any cinema leaning on 2 Homepods (original or Jr). Instead, they have
true surround sound setups with dedicated front left & right, center and at least rear left & right speakers... if not additional speakers for 7.1 or even ATMOS setups. There's no way to match that with
ANY 2 speakers (or a soundbar, even if the marketing and/or name of the soundbar implies they are "surround" or even "ATMOS").
If you want home theater sound to pair with that big screen, my suggestion:
- Get a nice-to-great receiver to act as your central audio-video hub. A few hundred will get you into nice range. A bit more can get into great.
- Since stereo is good enough for you for now, start with 2 nice speakers for front left & right. Just about ANY two will sound better than the stock speakers in the TV. #1 and #2 will cost more than a pair of HomePod Jrs but if you choose quality, they will sound as good if not better and be the foundation for a richer audio experience as you progress down this list. They will also get you massive playback flexibility well beyond the walled garden limits imposed by Homepods.
- When you can, add a center speaker to go right under/over the TV. With #1 & #2, this will likely sound better than any 2 mini speakers you can get even if you don't go any further from here.
- When you can, add a good-to-great subwoofer for bass (that no tiny little speaker(s) can replicate simply because of size). If you have "I like deep bass" ears, this will be better than you could ever accomplish with ANY tiny speakers.
- When you can, add 2 nice rear left & right speakers. This gets you "room filling" experiences that are NOT faux effects. Your ears will notice the difference of sound actually coming from behind you vs. computational tricks from speakers sitting somewhere out in front of you. At this point, you would be set up for Dolby Digital and DTS 5.1 surround. For many, this can be the end point of speaker purchases and will sound great... far better than you can get from any 2 little speakers paired as stereo.
- If you like, add 2 nice rear speakers to achieve a 7.1 surround setup.
- If you like, add some overhead/ceiling speakers for ATMOS.
Anything you watch via AppleTV or anything else with at least Dolby Digital 5.1 will sound MUCH better with a dedicated surround sound system than you will get out of any pair of stereo-limited speakers. There's no way to magically fake sound coming from a real surround sound setup. If there was, movie theaters would cheap out with only 2 speakers up front.
If you want Homepods for airplay purposes, choose #1 with Airplay 2. There's plenty with it and it works great. If dollars are a little tighter, you can always airplay to AppleTV to make a receiver without it play whatever you are throwing to your home theater speakers. However, airplay built into receivers is very nice and seemingly nominal in terms of adding cost.
Apple has not yet chosen to directly address the niche want of a
true surround sound setup with homepods- else they would have a marketed option to buy upwards of 5+ Homepods and some kind of Apple-built subwoofer. Apple people are trying to force this and spinning all kinds of ideas about why this is ideal... but I suspect much of that is because they want to buy only Apple and/or they've been fooled by others who up to outright lie that one can do with 2 what actually works with 5 or more, plus subwoofer.
All that offered, Homepods do sound nice and if stereo is actually good enough for you, they are nice little speakers that have good sound for their size. Good speakers are often usable for a decade or more (if they don't have walled garden/software limitations over such a span) so they represent a consumer purchase with usefulness far longer than what you will pay for several generations of iPhones, Macs, iPads, etc. My suggestion is always the same: buy accordingly.