Ubuntu 20.04 has no installation candidate for php8.1-sqlite

Apparently package php8.1 is available for ubuntu 22.04 but not available for 20.04. php7.4-sqlite is, however, available for 20.04.

In particular I'd like to use PDO with sqlite on PHP8.1 on 20.04, What are my options to make this happen?

I've already altered /etc/php/8.1/cli/php.ini in anticipation of this working. I found instructions for building libsqlite3.so here - and with that, I was able to compile the library. Then I issued:

sudo mv libsqlite3.so /usr/lib/php/20210902/sqlite3.so

But when I ran php -v, the error log said:

[29-Jul-2023 18:26:13 America/New_York] PHP Warning:  PHP Startup: Unable to load dynamic library 'pdo_sqlite' (tried: /usr/lib/php/20210902/pdo_sqlite (/usr/lib/php/20210902/pdo_sqlite: cannot open shared object file: No such file or directory), /usr/lib/php/20210902/pdo_sqlite.so (/usr/lib/php/20210902/pdo_sqlite.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
[29-Jul-2023 18:26:13 America/New_York] PHP Warning:  PHP Startup: Invalid library (maybe not a PHP library) 'sqlite3' in Unknown on line 0

(This is different from the prior error messages, which were:

[29-Jul-2023 18:24:29 America/New_York] PHP Warning:  PHP Startup: Unable to load dynamic library 'pdo_sqlite' (tried: /usr/lib/php/20210902/pdo_sqlite (/usr/lib/php/20210902/pdo_sqlite: cannot open shared object file: No such file or directory), /usr/lib/php/20210902/pdo_sqlite.so (/usr/lib/php/20210902/pdo_sqlite.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
[29-Jul-2023 18:24:29 America/New_York] PHP Warning:  PHP Startup: Unable to load dynamic library 'sqlite3' (tried: /usr/lib/php/20210902/sqlite3 (/usr/lib/php/20210902/sqlite3: cannot open shared object file: No such file or directory), /usr/lib/php/20210902/sqlite3.so (/usr/lib/php/20210902/sqlite3.so: cannot open shared object file: No such file or directory)) in Unknown on line 0

(And, yes, I understand that even if that had worked, it likely would not have solved the PDO problem.) So I'm not sure how I can proceed to get this functionality for PHP8.1 on Ubuntu 20.04. Is there another package, or maybe a non-standard source from which I can get a working PDO + SQLITE3 (or at least PHP + SQLITE3) installation? Web searches in this case, with the appropriate keywords, have not helped (other than the afore-mentioned library compilation). Or maybe the compile option is still valid but there are steps missing?

EDIT

This was the sqlite3 library compile command:

gcc \
    -Wl,-soname,libsqlite3.so.0 \
    -DSQLITE_ENABLE_COLUMN_METADATA \
    -DSQLITE_ENABLE_DBSTAT_VTAB \
    -DSQLITE_ENABLE_FTS3 \
    -DSQLITE_ENABLE_FTS3_PARENTHESIS \
    -DSQLITE_ENABLE_FTS3_TOKENIZER \
    -DSQLITE_ENABLE_FTS4 \
    -DSQLITE_ENABLE_FTS5 \
    -DSQLITE_ENABLE_JSON1 \
    -DSQLITE_ENABLE_LOAD_EXTENSION \
    -DSQLITE_ENABLE_PREUPDATE_HOOK \
    -DSQLITE_ENABLE_RTREE \
    -DSQLITE_ENABLE_SESSION \
    -DSQLITE_ENABLE_STMTVTAB \
    -DSQLITE_ENABLE_UNKNOWN_SQL_FUNCTION \
    -DSQLITE_ENABLE_UNLOCK_NOTIFY \
    -DSQLITE_ENABLE_UPDATE_DELETE_LIMIT \
    -DSQLITE_HAVE_ISNAN \
    -DSQLITE_LIKE_DOESNT_MATCH_BLOBS \
    -DSQLITE_MAX_SCHEMA_RETRY=25 \
    -DSQLITE_MAX_VARIABLE_NUMBER=250000 \
    -DSQLITE_OMIT_LOOKASIDE \
    -DSQLITE_SECURE_DELETE \
    -DSQLITE_SOUNDEX \
    -DSQLITE_THREADSAFE=1 \
    -DSQLITE_USE_URI \
    -shared \
    -o libsqlite3.so \
    -fPIC \
sqlite3.c